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Vert Morph Notes

by: Hayley Busch

Vert Morph Notes Biosc 1200

Hayley Busch
Vertebrate Morphology Notes
Dr. Bledsoe

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About this Document

These are my notes from day 1 till the last day of class. They're very thorough and I attempted to write down everything Dr. Bledsoe said so that I wouldn't miss anything later while studying for ...
Vertebrate Morphology Notes
Dr. Bledsoe
Study Guide
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This 64 page Study Guide was uploaded by Hayley Busch on Friday February 13, 2015. The Study Guide belongs to Biosc 1200 at University of Pittsburgh taught by Dr. Bledsoe in Fall. Since its upload, it has received 384 views. For similar materials see Vertebrate Morphology Notes in Biology at University of Pittsburgh.


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Date Created: 02/13/15
Vertebrate Morphology Phylogeny anal Classi cation Phylum Chordata o Vertebrates are chordates 0 Root quotchordquot Notochord 0 Membership craniates and socalled protochordates 1 Craniates quotBraincase 2quotProtochordatesquot Root quotprotoquot quotchordquot o Earlyoriginal chordate Members of this group are not each other s closest relatives quotationsquot 0 Not a clade o Tunicates Urochordata seasquirts Root uro chord quotTailquot chordate Protochordates o Lancelets cephalochordata Second protochordate group Root quotcephaloquot quotchordquot Head quotchordatesquot 0 Not actually a head misleading root 0 Refers to slight elaboration of the anterior head Nothing like the craniates o Craniates craniata Include the vertebrates Root cranium quotBraincase o Cephalochordata and craniata are each other s closest relatives Protochordates form a glade not a clade Nonmonophyletic group Chordate Characteristics Nonexclusive characteristics Eukaryotic possession of a nucleus 0 Triploblastic 3immature stage of organisms three primary germ layers 0 Ectoderm mesoderm endoderm Skin NS ectoderm Eucoelomate root eu quottruequot 0 Coelomate body cavity 0 True body cavity 0 Having a mesoderm lined coelom o Metameric o Meric quotunitquot 0 Meta quotseriesset o Chordates are segmental bilateral IO Pharyngeal pouches or slits quotpocketsquot or holes in the throat Hemichordates and chordates are close evolutionary relatives Exclusive traits Dorsal hollow nerve Chord 0 Most have a ventral solid nerve chord Notochord o Skeletal tissue 0 Hydrostatic skeleton 0 Doesn t persist into adult just developmental period lnduces overlying ectoderm to create dorsal hollow nerve chord lnduces nerve chord formation 0 Just ventral to the nerve chord Subpharyngea gland Root sub quotbelowquot Root pharynx throat Below the throw 0 An embryonic outgrowth of the pharynx throat o Takes two forms Endostye Eurochordates cephylochordates ln craniates only two have endostyles young hag shes and young lampreys Thyroid produces thyroxin Endocrine gland directly into bloodstreamno duct Thyroxin controls the rates of cellular metabolism Hypothyroidism abnormally low rates of cellular metabolism weight gain Hyper abnormally high rates weight loss Similar in development and position and similar chemical products speci cally containing iodine ln lampreys larval endostyle is converted into adult thyroid Therefore they are probably homolooous Similarities in shape and form Larval lamprey s endostyle becomes adult thyroid suggests that the thyroid evolved from the endostyle Generalized chordate note structures we ve discussed and Buccalcav y Gut Caudal region Pharyngeal arches Pharyngeal or gill slits Anus is called subterminal It isn t at the end of the animal De nes two regions of the animal precaudal and caudal region o Caudal tail 0 Chordata have a tail after anus Before pharyngeal pouches open developmental several of these Wall is thicker between the patches thicker part of the pharyngeal pouch Craniates hemichordates Eurochordates the pharyngeal pouches slit open gills grow into these spaces 0 The pouches slit open by programmed cell death apoptosis The quotProtochordatesquot Urochordata o Larvae closely resemble generalized chordate g 27 0 Figure 27 Traits o Notochord shared with cephalochordates and craniates o Pharyngeal slits exclusive 0 Endostyle o Sessile adults with tunic af xed to a surface 0 Figure 0 Adult is completely saclike Dorsal hollow nerve chord isn t there anymore Retain endostyle secrete mucus into pharynx Water into enchorosidym Water comes out pharyngeal slits and water goes out excurrent siphon Tunic tunicen is the protein Nearly identical to cellulose found in plants The Cephalochordates gure 28 0 Have nonexclusive and exclusive chordate characteristics PLUS they have characters that link them to craniates clade o Distinct anterior and posterior ends including a postanal tail craniates have Distinct somewhat elaborated Not much going on at anterior end for the other chordates but is for cephalo o Myomers quotMyoquot muscle quotMericquot units Segmental axial musculature Nothing exactly like that in urochordates Have aggregates of neurons but not in musculature 0 Blood ows forward ventrally caudad dorsally change in position of the heart Others have blood ow forward dorsally caudad ventrally 0 Figure 28 Craniates Traditionally Vertebrata divided among eight classes 0 Old class names not clades in parentheses quotAgnathaquot jawless shes quotPlacodermiquot placoderm shes quotOsteichthyesquot bony jawed shes Chondrichthyes cartilaginous shes 00000 0000 quotAmphibiaquot amphibians quotReptiliaquot reptile Aves birds 0 Mammalia mammals Formal modern approaches 0 Abandon traditional classes 0 De ne vertebrates differently Craniata brain case Hag shes have no vertebrae o Jawless shes 0 Produce copious amounts of mucous Vertebrata have vertebrae The two groups together describe craniata called sister groups 0 All craniates possess the characteristics of the Chordata either in unmodi ed or modi ed form 0 The unmodi ed and modi ed forms are homologous Subpharyngeal gland Protochordates have an endostyle in larvae and adults Craniates excluding lampreys have thyroid modi ed form of endostyle All possess these characters that link craniates and cephalochordates o Myomers 0 Blood ow 0 Anterior end is elaborated really true in craniates All craniates possess many exclusive craniate characters evolutionary novelties that delimit the Craniata o quotDelimitquot to circumscribe or to establish We ll concentrate on ve such characteristics 0 Ectodermal placodes o Ectodermal one of the three germlayers quotPlacodesquot refers to plate Also known as sensory placodes Associated with the special senses Two kinds Neurogenic 0 Give rise to neurons Sensory neurons 000 0 Lens 0 Give rise to the lens of the eyes 0 Neurogenic and lens placodes 0 Also known as sensory special senses 0 Form by invagination of ectoderm into underlying mesoderm quotlncleftingquot Mesoderm grows into underlying ectoderm o Lips press together and pinch off platelike structure ectodermal placode Most placodes are hollow sometimes the space disappears but most of the time the space is lled with uid Placodes Special Senses Olfactory Smell Optic Vision Otic Hearing and balance Lateral line Pressure sensing shes Gustatory Neurons of taste buds Only the lens placodes aren t neurogenic Olfactory Placode 0 First moving caudally o Is usually paired 0 Process of olfactory stimuli by the forebrain 0 Lens 0 Second moving caudally o Nonneurogenic o ALWAYS paired o Stimuli processed in midbrain 0 Third moving caudally o AWLAYS paired o Stimuli processed in hindbrain 0 Lateral Line 0 Two on either side of Otic paired on the other side 0 Caudal and Cranial Both have pairs L to R Not all Craniates have them Hindbrain Caudal are meant to be bigger than the cranial Lost in adult tetrapods Exclusive traits cont 0 Tripartite Brain 0 Expansion of anterior end of dorsal hollow nerve chord Neural Crest 0 Unique embryonic tissue arises from ectoderm alongside developing neural tube Neural tube is right along the dorsal midline strips on left and right along the developing neural tube Unique tissue These neural cells operate as embryonic stem cells 0 They aren t pluripotent can t give rise to everything 0 Forms diverse structures including Nerve ganglia Group of neuronal cell bodies in the PNS Pigment cells Dentine One of the hard tissues of teeth Neural cells that secrete dentine Pharyngeal skeleton OOOO o Pharyngeal arches are thicker the skeleton forms within the arches Adrenal medulla Endocrine gland Ad quottowardadjacent toquot 0 Renal Kidney 0 Outer region cortex inner region medulla Cells produce compound similar to epinephrine 0 So many things form from neural crest cells 0 Bone no other organism besides craniates have bone may have hard tissues 0 Composed of hydroxyapatite deposited around a mesh of collagen bers Hydroxyapatite is composed of a mineral form of calcium phosphate The hard phase of bone is calcium phosphate Embedded in the matrix are a bunch of collagen bers high tensile strength Collagen is a protein 0 Bone biomechanically is biphasic Mineral phase and the protein phase Increases the strength of bone Braincase another exclusive trait 0 Protective case of cartilage bone or both around the brain ORIGIN OF CHORDATES Phylum Hemichordata acorn worms 0 More like echinoderms than chordates Echinoderms sea stars sea urchins 0 Yet they possess pharyngeal slits Chordates have them also one of the nonexclusive traits only hemi and chordates have them 0 Figure 23 Marine organisms mud dwellers Takes in water through mouth lters the water through the pharynx and takes in plankton and such and then water leaves through the pharyngeal slits Protostomes and Deuterostomes 0 Most animals are protostomes quotProtoquot rst quotStomesquot openings Mouth forms rst 0 quotDeutoquot second Anus forms rst Mouth forms second Synchronized cell cleavage cleavage o Indeterminate when they cleave the early cells are totipotent can give rise to anything Determinate aren t totipotent Monozygotic twinning is like indeterminate 0 Figure 24 Radial cleavage is a novel state found in Deutoerostomes O o Blastopore is opening to stomach area Digestive tract in adults 0 One of nonexclusive traits of chordate is that they re a eucoelomate 0 Formation of Coelomate Protosome pseudocoelomate Strips on either side of the Archenteron Splits off to yield the coelom Schizocoely Outpocketing on Deuterostome evagination Mesoderm forms by pinching off the Archenteron Coelom is formed by enterocoely o Pinch off 0 Larval Protostomes surface of larva there isn t any cilia Deuterostomes have ciliated band at larval stage 0 Doesn t know function of ciliated cells 0 Possession is ancestral amongst Deuterostomes although lost in adu s 0 Strong evidence that all Deuterostomes are more closely related than anything else Form a clade 0 Fossil forms 0 1 Calcichordates cornuates Openings in some that look like pharyngeal slits debatable but in the rest of the anatomy they re rather echinodermlike debate about where t in 0 May be closest relatives of chordates uncertain o 2 Pikaia UNDERLINE OR WRITE IN ITALICS ON THE EXAM The earliest fossil chordate Dark strip running down the center evidence of a notochord Strips running down either side of the notochord myomeric Looks like a cephalochordate notochord and myomeric o Closest to cephalochordate craniates Evidence of a clade Clades Synapomorphies Craniata Ectodermal pacodes Neural crest Bone Tripartite brain Braincase Cephalochordata Buccal cirri Urochordata Fibrous tunic Tunicen celluloselike Hemichordata debate if form a clade Proboscis and Collar Echinodermata Bipinnaria larva Larger Clades Somitochordata sister group is Urochordata Myomeres Distinctive blood ow pattern caudad dorsally Anterior end is elaborated Chordata sister group is Hemichordata Notochord Dorsal hollow nerve chord Endostyle Postanal tail Pharyngotremata sister group is Echinodermata Pharyngeal slits Deuterostomata Blastopore becomes the anus Radial indeterminate cleavage Looped ciliated band Eucoelomate Get the branching patterns and relative position of origin from the synampomorphies Systematics and Evolution 0 De nitions 0 Systematics the study of the nature and causes of organismal diversity The nature of organismal diversity description of organismal diversity who s related to whom The way in which things come to be The causes the mechanisms by which these things have taken place how things happened modi cations in development result in synampomorphies o Taxonomy the science of naming and classifying groups of organisms taxa s taxon Geological time 0 Absolute time time measured in years using radiometric dating Halflife of an unstable isotope can compare unstable to stable isotope in a fossil and can gure out when the animal died wouldn t be any more turnover after they died 0 Relative time the relative occurrence of events through time Neural crest developed later than dorsal hollow nerve chord DHNC chordata preceded the neural crest development craniata Comparison of absolute times to determine relative times Stratigraphic dating independent approach using independent 0 Present in sedimentary rock 0 Sediment pours into lowlevel ground and what happens in those sedimentary columns is that the sediment above presses down lower level to create stratalayers the sedimentary layer at bottom would be older than those at the top so can use the layers to determine time Index fossils correlate strata at different geographic locations 0 Restricted to the speci c layer 0 Many index fossils that are unique to that layer and each layer has them Geomorphology Ex using the degree of erosion to establish relative ages of an island Fission track dating 0 Section off a rock thinly so light passes through the rock and know there s a radioactive isotope but don t know initial ratio of stablenonstable isotope can t do radioactive dating 0 See the tracks in the rock cut it up thin and can count the number of tracks if the rock is young there will be fewer tracks because there hasn t been enough time for tracks to accumulate o Important point Although they each rely on different principles they yield the same relative time independent methods yield the same relative times The Fossil Record 0 The fossil record 0 The body of information contained in Earth s fossils 0 Fossil a preserved remain or trace of prehistoric life Main modes of fossilization o In sediments either with or without petri cation 0 Soft parts degrade easily and don t fossilize only the hard parts bone shells etc 0 Sometimes the fossil retains the actual material 0 Sometimes the pressures of overlying sediment are so high the minerals get replaced into other materials the fossil turns into rock petri cation In sediments as impressions or carbon lms 0 Leaves have most materials removed except carbon so creates a leaf shape lm 0 Dinosaur footprints Stride length of dinosaurs Other modes 0 Peat or tar 0 Peat is organic matter built up typically in bog settings so can be preserved that way 0 Tar seeps on the surface of the Earth Deep 20 meter animals see the surface of the tar and it looks like water and then can t get out and predators go in after and also get stuck Amber 0 Amber is fossilized tree resin 0 Freezing o Drying o By mummi cation 0 Ex organisms get stuck inside a lava tube that had cracked open and can t get back out and get mummi ed 0 Problems with fossil record Darwin recognized this 0 Limitations of the fossil record Bias some organisms eg marine are more likely to be preserved than others eg upland terrestrial 0 Die and fall to bottom and get preserved in the sediment o The terrestrial are less likely to be preserved in the sediment lncompeteness some fossils remain undiscovered or are destroyed by geological processes decay or scavenging may prevent fossilations Subduction one of the plates moves against another plate and gets forced under subducted another plate and melts away lost Scavenging mammals or decay by bacteria These lead to gaps in the fossil record Lessons from the Fossil Record 0 Different groups arise at different times Somitochordata Pikaia allows us to see when Somitochordata arose at least 531 years ago 0 A historical sequence of ecosystems is revealed Can put together a view of biotic and abiotic circumstances that were occurring at that time Can study how ecosystems abioticbiotic have changed over time 0 Fossil sequences show evolutionary transformations Stratigraphic control have a good idea of what was aroundit is good 0 Reconstruct evolutionary history of something like horses 0 Can see a series of changes that lead to what it is todaysize increased legs elongated etc Size probably increased because Of saber tooth cats were too easy of prey 0 Have to avoid predators Other interpretations Legs elongated increased running ability in plains environments Evolution of attributes Goals in evolutionary morphology o 1 To identify evolutionary changes in form and attendant function 0 2 To order these changes in relative time ie on a phylogeny o 3 To specify the modi cations of development that are responsible for the origin of novel morphologies If an adult has a novel attribute that attribute has to have a basis of change D Evolutionary patterns 0 Phylogeny branching pattern that has yielded group s diversity 0 How to get at phylogeny Cadistic Analysis Evolutionary detective work Basic ideas 1 When a character evolves the earlier form is the ancestral state 2 The new modi ed form is the derived state 3 Because derived state evolved later taxa which possess it must share a more recent common ancestor with each other than with any other organisms 4 Therefore derived states shared between species delimit dades o Paired appendages Two forms Fins o Limbs Lobed n shes o Similarities suggest homology to limbs See both lobed ns as fossils and also see the earliest limbed craniates Question becomes which ns or limbs evolved from what 0 Limbs from ns limbs are the later derived state ns are the earlier ancestral Earliest tetrapods had limbs and if that species had descendants the descendants would have limbs would further descendants would have them and so it would continue to spread via speciation sharing of the derived states means they share the closest ancestor and are closer than any other species on Earth Cade consists of an ancestral species all of its descendants and only those descendants 0 Use the sharing of the derived state between species to establish clade membership Limbs would be a synampomorphy of tetrapoda Evolutionary Morphology 1 Introduction 0 How do animals evolve Descriptive answer Analysis of causal mechanisms 0 How has it happened 0 Natural selection o If can identify how it s modi ed and provide explanation of how have good idea of causal mechanisms 0 Adult evolutionary transformations occur via modi cations of development Propose that these transformations are adaptations 0 Embryonic adaptations occur in the same manner 0 2 Biogenetic law 0 E Haeckel 18341919 quotOntogeny recapitulates phylogenyquot Ontogeny series of stages and associated processes during development Phylogeny describes pattern of ancestry and decent during diversi cation of a group 0 Can gure out phylogeny by looking at ontogeny of descendants o Replays the phylogenetic history 0 That isthe ontogenetic stages of a descendant lineage represent the adult stages of its ancestors Two basic ideas 0 Terminal addition 0 New stages yielding derived adult morphology added onto the end of the ancestral ontogeny New developmental stages added onto the end 0 Example Ancestral ontogeny A l B l C o A earliest stage 0 C adult stage 0 B developmental stage in between Descendant ontogeny 0 A I B I C I D new stage added on at the end Next descendants ontogeny ADBDCDDDE o E adult stage 0 Can read them back in evolutionary time to gure out the development Interpret C as a developmental stage but as the adult stage in ancestors Replayreadback and gure out pattern of ancestry and descent o Haeckel Second part Condensation development accelerates Therefore each stage is shorter than it is in ancestors Accounts for the large number of evolutionary changes but have them develop in a reasonable amount of time Paingenesis change that adds to ancestral ontogenies Can consider this change the aggregate of change total 0 Or change that s consistent with terminal addition Cenogenesis change that does not t recapitulation eg trophoblast placenta o Synapomorphy delimits changes assumes the groups are homologous palingenic o Homoplasy confuses cenogenetic Theory discarded too much cenogenesis new structures can arise at any stage of development not just terminally studies of mutation showed this 0 3 Paleogenesis o quotDescendant ontogeniesm to recapitulate ancestral ontogeniesquot Not saying anything necessarily about phylogenies Only a tendency Development can be modi ed at any stage 0 The existence of heredity is the basis for the tendency or resemblance to replay ancestral ontogenies Ontogenies are hereditable 0 Example the notochord Present in all craniates earlier on in development tendency is to say that it s the resemblance for the adult stage but it s not Instead the descendants have retained the notochord embryonically even though doesn t persist in most craniate adults because it induces the neural plate then develop neural folds neural tube spinal chord 0 Example vestigial structures Retained in the adult as vestiges 4 Genetic basis of morphological evolution 0 Mechanism for adaptation natural selection 0 Genetic modi cations Changes in protein structure 0 Structural proteins as opposed to regulatory proteins Changes in regulatory mechanisms during development eg Hox genes 0 Genes that specify identity major axes of organs 0 This kind of change at the heart of most evolutionary novelties as modi cation of development 0 5 Modes of evolutionary change 0 Modes ways development can be modi ed 0 Here we discuss the tissuelevel processes that are affected by genetic changes that modify development How tissues form and interact are the heart of many genetic modi cation 0 A Cell division and allometry Rates of cell division can change during development giving rise to a change in proportions of different developmental stages Proportions of puppies amp babies etc are attractive Can be called quotdevelopmental allometryquot Allometric growth characteristic of all craniates Allometric growth different parts of the body grow at different rates Evolutionary allometry rates of cell division and hence growth of a developing tissue can change during evolution Such change gives rise to a descendant animal with different proportions than its ancestors In a descendant lineage if an alteration from one part from another from ancestor then the descendant will look different and have different proportions Ex titanotheres rhino ancestries o Evolutionary allometry change in relative rates of growth Horns are all different sizes different proportions in descendants than ancestors o B Cellular differentiation Cell populations may differentiate differently in descendant lineages Compared to ancestral lineages and how cell populations differentiate with idea that they may differentiate differently in descendants than in ancestral Ex Origin of cartilaginous skeleton in Chondrichthyes Synapomorphy loss of bone 0 Earlier craniates had bone 0 Traces remain in some sharks 0 Bonelike material present in scales and teeth Transformation Series No Bone l Bone l Loss of Bone Associated Developmental Series craniates with bone Fibroblasts l Cartilage l Bone Analysis Loss of bone is the further derived state look at the developmental series and look at how it s been modi ed The process that differentiates cartilage to bone is lost cell populations don t differentiate further from cartilage into bone Descendant ontogenies tend to resemble ancestral ontogenies Sequences resemble each other except for a derived state the last step is cut off and ends up with cartilaginous skeleton 6 Classi cation 0 A Craniate origins Uncertain Evidence that sister group is Cephalochordata share characteristics synampomorphies Somitochordata Origin probably associated with the origin of neural crest ectodermal placodes 0 Most of the derivatives of these are softparts don t fossilize well Lacking transitional forms a living or extinct form of that helps complete a transformation series Polarized set of character series Polarity directionality Transformation series No paired appendages ancestral state within craniata l paired ns l paired limbs Tetrapoda is the clade No inner ear l inner ear don t know the transformations don t know the series of changes Don t know the transitional forms of the origins of craniates o B Traditional classi cations 8 classes Those in marks are monophyletic won t use those names 0 C Phylogenetic Classi cation Arranges classi cation according to phylogenetic branching pattern M H handout o D Major groups Handout Histology o 1 De nitions 0 A Tissue usually de ned as an aggregation of similar cells with similar func ons This is simplistic and misleading bad de nition Le Gros Clark has provided a better de nition an assemblage of cellular and brous elements in which on particular type or ber usualy predominates organized to form the material basis of one of the functional systems of the body structure and function 0 Example matrix within all cells exist in the blood plasma erythrocytes predominate in the blood blood is a tissue 0 Forms the stuff of in part the cardiovascular system functioning in an important way along with other tissues have the cardiovascular system work 0 B Histology the study of anatomy at the tissue level of organization Additionally he would add 39the study of microscopic anatomy onto the de nition 0 C Kinds of tissues 1Ep heHa 2 Connective tissues adipose falls into this 3 Supporting tissues some would put them in with connective but distinct enough 4 Blood and related tissues 5 Muscle 6 Nervous tissue 0 2 Epithelia s epithelium o Sheetlike tissues that cover free surfaces or line ducts sacs or tubes and are attached to a basement membrane 0 A Types of epithelia Described according to three criteria Strati cation layers of tissues 0 Simple one layer of cells Cells are attached to extracellular matrix know as the basement membrane part of the epithelium that lies right next to the underlying connective tissue Epithelia right next to the cells that are lined free surface 0 Part of epithelia right next the lumen Lumen space right Strati ed more than one layer of cells Not all cells reach the bottom surface Only the basal cells attach to the basement membrane Pseudostratified all cells attach to the basement membrane but only some reach the free surface Transitional specialized form lining urinary bladder and capable of great distension Number of layers you count on the epithelium changes as the bladder lls up 0 Cell shape classify by reference to cells at the free surface 0 Squamous the cells are at wider than tall 0 O Cuboidal cells are cubeshaped Columnar the cells are columnlike taller than wide Specialization O O Glandular secrete products Secrete products onto the freesurface Ciliated cells at the free surface bare cilia Can be both glandular and ciliated throat Sensory typically sensory epithelia basal layer attach with the neuron O Typically synapse with cells Corn ed impregnated with keratin Ex Products with keratin for epidermis Ex Finding sharp stuff in turkeys because they re epithelium is so corni ed so strong 0 Absorptive brings in via phagocytosis or endocytosis Epithelial of gut Epithelia are described by combinations of terms Eg human epidermis is a squamous strati ed corni ed epithelium Eg intestinal villi are covered by a simple columnar glandular epithelium o B Glands Organs that secrete products and are derived from epithelia developmentally Neural crest isn t derived this way 1 Endocrine secrete products directly into the bloodstream eg thyroid adrenal ductless AND Exocrine secrete products through a duct into a free surface eg liver pancreas O O O Gland is connected physically to the epithelium from which it developed Liver Produces bile and secretes bile through a duct onto a free surface of the gut duodenum of the small intestine Outgrowth of the developing gut Pancreas can be both other ones are like this too 2 Unicellular consists of a single cell and multicellular O Unicellular glands there s effectively no duct use exocytosis Goblet cell epithelium 3 Simple unbranched vs compound branched 0 Simple single lobe amp single unbranched duct 4 Types of secretion merocrine apocrine holocrine O Merocrine occurs by exocytosis membranebound vacuoles within cells fuse with the plasma membrane ALWAYS exocrine but exocrine isn t necessarily merocrine Apocrine tip of the secreting cell breaks off and some of the plasma membrane are released some gets onto free surface quotApoquot tip ONLY in exocrine glands Can t be endocrine because would get pieces of plasma membrane directly into the bloodstream Holocrine quotwhole or entirequot The entire cell is shed and breaks open to release product onto the free surface Restricted to exocrine glands 2 Connective tissues 0 A Mesenchyme embryonic and fetal tissues Covered under connective tissues but some of them aren t connective Irregular starshaped cells with large intercellular spaces Differentiate into other cells types Most will differentiate into connective Most mesenchyme cells are mesodermal neural crest being the biggest exception Extra and intra cellular is important 0 B Cellular components of adult connective tissues 1 Fibroblasts Collagenous and elastic bers Secrete a uid ground substance 2 Macrophages Phagocytic immune system cells 3 Mast cells lmmune cells that secrete histamine 4 Fat cells 0 Function in the storage of fat 0 Large vacuole inside full of fat so large that it almost takes up the whole cell 5 Plasma cells 0 Typically immune system cells like leucocytes 0 Although possible RBC s aren t a common component of connective tissues unless there s an injury Extracellular components 1 Collagenous bers 0 High tensile strength made up of collagen 2 Reticular bers 0 Extremely thin ne bers typical of loose organs like the pancreas and liver 3 Elastic bers 0 Can stretch and retain their original state 4 Ground substance 0 Sometimes called uid ground substance Acts as the uid diffusion medium of the tissue 0 Gas exchange by diffusion release their wastes which move by diffusion the vascular movement through the ground substance 0 D Types of connective tissue 1 Loose connective tissue Characterized by 0 Loose networks of collagenous and some elastic and reticular bers 0 Fibroblasts Mast cells Macrophages Clusters of fat cells 0 Leukocytes Human epithelia is strati ed squamous and underneath is the dermis which is loose connective tissue 2 Dense connective tissue Tendons ligaments capsules etc o Tendons attach muscle bers to skeletal elements like bone Achilles tendon contraction of skeletal muscles means the tendons have to be strong to keep things attached 0 Ligaments are structures that attach adjacent skeletal elements to one another ACL 0 Capsules are structures typically associated with joints Synovial joints like the knee caps Extracellular bers predominate 0 Very very few cells 0 Almost no ground substance 0 3 Supportive tissue bone cartilage notochordal tissues have an extensive semisolid intercellular matrix 0 Bone hard part hydroxyapatite and mineral part is collagenous bers semisolid 4 Blood and related tissues 0 5 Muscle 3 types 0 Smooth visceral o Skeletal 0 Cardiac 6 Nervous tissue 0 Neurons and accessory elements eg neuroglia o Neurons are excitable de and repolarize involved in many functions of the body 0 There are also accessory elements that provide for physical support and nutrition not excitable Embryology 1 The egg 0 A Eggs and ova Ovum p ova female gamete haploid Egg the ovum plus accessory materials 0 Some craniates use egg as a differentiation from ovum when have accessory but some use them interchangeably if no accessory o B Egg types Microecitha little yolk that s evenly distributed synapomorphy of Theria 0 Micro small quotlecithalquot lecithin component of yolk Mesolecitha moderate amount of yolk unevenly distributed Lissamphibia many Pulmovertebrata OOO Macroecitha much yolk cytoplasm limited to germinal disc blastodisc some Actinopterygii Chondrichthyes nontherian Amniota o This indicates at leastthree different origins 2 Blastula uid lled ball of cells 0 A Types of cleavage early synchronized cell divisions Difference depends on amount and position of yolk Holobastic entire zygote divides yolk intracellular occurs in micro and mesolecithal ova Yolk is restricted to the vegetal path but indeed it has cytoplasm split it into 2 cell stage each cell having 12 of original yolk then splitting into 4 etc quotBlastquot immature stage of development Merobastic only blastodisk divides yolk is extracellular occurs in macrolecithal ova Ex in chickens o B Craniate blastulae 3 Gastrula Gastrula stage is achieved by gastrulation establishes the three primary germ layers 0 Establishment is critical with further development of blastoderm Establishes the primitive gut archenteron Establishes the positionthe opening to the archenteron opening is known as the blastopore All of the three main axes are established at the end of gastrulation left to rightmidline dorsalventral cranialcaudalanterior posterior Sets up the embryo for the formation of organs 0 A lnvagination and involution Cells of the margin of the gray crescent invaginated to form a cleft Gray crescent visible under the microscope pigmented o Cytoplasm shifts to reveal the pigmented area 0 Shifts it 180 degrees from the origin 0 Cells of the margin invaginated and form a cleft start of the archenteron Opening is the blastoderm o Becomes the anus 0 Sets up the cranialcaudal axis 0 Result of the position of fertilization sets up the cc axis 0 Caudal side 180 degrees from cranial Dorsalventral axis also set up 0 The ventral corresponds to the vegetal side endodermal cells 0 The dorsal corresponds with the animals side Archenteron forms Opening of the cleft is the blastopore Then cells move toward the blastopore and roll over its lip these then move forward under the surface this is involution They slide in a cranial direction underthe surface cells 0 In in quotvolequot rolling o lnrolling going from the surface and rolling forward underneath the cells at the surface 0 B Archenteron and blastopore O O Archenteron formed by invagination and involution becomes adult gut 0 Both o It becomes through development the adult gut Opening so formed is the blastopore becomes the anus o quotPorequot opening quotblastoquot earlyimmature Don39t confuse with blastocoel quotcoelom cavityquot obliterated during gastrulation and no opening to the blastocoel o The blastocoel is obliterated during involution Endodermal cells protrude into blastopore forming yolk plug 0 Yolk plug will be pulled back into the blastopore and an opening is formed again 0 Cells on outside fated to become ectoderm yolk cells fated to become endoderm C Mesoderm formation During gastrulation there are two different kinds of mesoderm produced lnvolution yields chordamesoderm on midline of the archenteron roof Chordamesoderm is the mesoderm that will give rise to the notochord lnvolution surface cells roll over the dorsal lip of the blastopore and slide under the surface cells 0 The cells in the middle of the archenteron will move o If on midline of the roof they are dorsal o If cranial caudal of the midline will specify the leftright axis Lateral involuted cells become prospective mesoderm Lateral because they are left and right of the strip 0 Become the second kind of mesoderm prospective o Gives rise to all of the other mesodermal derivatives other than the notochord Some cells late in involution involute on the ventral blastopore lip and become prospective mesoderm Mesoderm is proliferating between the endo and ectoderm 0 Where it will reside In late gastrulas mesodermal cells proliferate and expand between ectoderm and endoderm 0 As a result end up with the three primary germ layers Figure 413 p138 embryology 4 shows epiboly with an arrow uses Lissamphibia as ex D Epiboly Rapid surface cell movement occurs not all cells involute Surface cells become ectoderm Surface cells expand to clothe embryo in ectoderm End up with blastopore which will become the anus The blastopore has yolk plug in the middle 0 This will regress back into the embryo o Ectoderm won t cover the blastopore Yolk plug remains ectoderm free 0 What happens in other egg types 0 Need to look at macrolecithal types 0 E Macrolecithal development Chicken for an example Blastodisc separates into epiblast surface and hypoblast deep layers 0 This separation is the process that yields the blastula stage in macrolecithal forms The space between the epiblast and hypoblast is probably homologous to blastocoel o Blastula is a ball of cells with uid lled inside Flattened blastula Embryology 5 Peripheral epiblast cells move toward center form primitive streak Simply a trough along the cranialcaudal axis Cells ingress through the streak to form mesoderm and endoderm o Functionally ingression is comparable to involution they re different processes lnvoluted cells become mesoderm lngression cells become mesoderm Blastocoel is obliterated in both Area below the endoderm will become the archenteron Hard to see because yolk is extracellular and the yolk sac hasn t formed yet 0 4 The Neurula o The beginning of the developmental formation of organs orgagenesis o The start of neurulation dorsal hollow nerve chord o A Formation of the neural tube and neural crest Chordamesoderm notochord either one works at this point induces neural plate formation rst thing to happen 0 The notochordal cells send a signal to the overlying ectoderm instructing those cells to become the neural plate induction 0 Induction a process by which one embryonic tissue causes an adjacent tissue to differentiate in a particular way 0 A critical process common during craniate embryonic development 0 Also changes in patterns of induction yield derived states 0 Induction usually occurs between an epithelium and a mesenchymal tissue 0 Critical step because of dorsal hollow nerve chord Chordamesoderm is mesenchymal o Chordamesoderm induces the overlying ectoderm into the neural tube Neural crest forms in lateral folds of the developing neural tube 0 Can see referencing to embryology 6 0 Cells are fated to become neural crest migrate away and proliferate between skin ectoderm and neural foldneural tube 0 Migrate throughout the body to form the range of tissue and structures 0 No growth of embryo starts at beginning of neurulation o B Differentiation of the mesoderm Ventral expansion 0 Throughout gastrulation the embryo didn t not grow in size Closure of endodermal tube Differentiation of coelom Mesoderm splits to form coelom 0 Secondary schizocoely Differentiation of mesoderm yields three regional divisions Epimere dorsal segmented mesoderm each segment being a somite 0 Also known as paraxia mesoderm 0 Initially mesoderm is continuous strip on each side of developing embryo then strip segments to yield somites Mesomere gives rise to the kidneys and gonadal ducts 0 Also known as intermediate mesoderm Called this because in between endomeric mesoderm and lateral plate mesoderm Hypomere 0 Also known as lateral plate mesoderm o Epimeric region consists of somites each with three regions 0 Dermatome forms the dermis of the integument o Sclerotome forms the vertebral column and parts of the skull o Myotome forms the somatic musculature of the body wall and appendages Lateral plate mesoderm has 2 regions 0 Splanchnic layer lateral most forms connective tissue visceral muscles mesenteries visceral peritoneum Visceral peritoneum peritoneum is the lining of the coelom visceral for this region 0 Somatic layer forms parietal peritoneum and body wall muscles 0 5 The pharyngula o A General organization and changes Pharyngeal region differentiates Other regions continue to differentiate Phylogeny8 Head tucked under 0 Olfactory is still more rostral o Tripartite brain 0 Brain is continuous with the spinal chord Lateral line placodes not present here Notochord is just ventral to the developing neural tube into the spinal chord and brain still present in this stage because induction happens throughout Stomodaeum precursor of the oral cavity 0 Primary germlayer that lines oral cavity is ectodermal o Pharyngeal pouches haven t split open yet for shes never for humans Pharyngeal closing plate bilayer consists of ectoderm and endoderm Heart is ventral to the arches blood is pumped dorsal caudad o Synapomorphy of Somitochordata o Precursor of the lung ventral evagination of the posterior oor of the pharynx 0 Most of the rectum lined with ectoderm o Ventral evagination is the lungs Embryology 8 o Cranial most part of intestine duodenum One outgrowth is the liver via invagination Endoderm Off of the liver there is a second invagination gall bladder function together Just caudal to those pair of invagination pancreatic buds of the pancreas dorsal amp ventral BiIobed organ 0 Single organ in adult humans Organs are suspended in the coelom Retroperitoneal to this are the kidneys Anal canal pracodeom is the precursor Ectoderm dangerous cancers Derivatives of the pharynx Thyroid forms by evagination of the midventral oor of the pharynx Craniate subpharyngeal gland Produces thyroxin controls cellular metabolism Pharyngeal pouch derivatives thyroid is not one Parathyroid produces hormones that control calcium and phosphate metabolism and bone development 0 Thymu lymphocyte production immune system organism Utimobranchia body originally considered vestigial in humans but now see it has immune system function clear it does have a function 0 6 Summary of Development 0 A Stages and processes see embryology 1 First unicellular zygotepharyngula o B The morphogenetic tree 0 7 Embryonic adaptations o A Needs of the embryo Oxygen food waste removal appropriate temperature protection Every craniate embryo develops in a aquatic environment to protect against desiccation o B The yolk sac An extraembryonic membrane for storage and absorption of yolk 0 Not part of the embryo extra 0 Associated with macrolecithal eggs Yolk sac is connected to the developing gut by the yolk stalk Look at embryology 8 Vitelline blood vessels invest the yolk sac o Vessels develop from the gut grow into the wall of the yolk sac o C The amniotic egg Synapomorphy of Amniota Chick as example macrolecithal egg Embryonic adaptations She not considered a membrane 0 There for protection doesn t allow liquid water to pass through but allows water vapor to pass egg has to breathe and protection from being broken open 0 Chorion an outer protective membrane and respiratory structure 0 Amnion containing amniotic uid 0 Embryo is bathed in amniotic uid Allantois acts as a storage area for uric acid also acts as a respiratory organ 0 Vascularizes the Chorion absolutely critical for gas exchange 0 Converts the Chorion into a respiratory organ in itself 0 Connection to the gut movement of blood between gut and Chorion o Yolk sac 4 extraembryonic membranes in the amniotic egg Chorion shell allantois amnion 0 Embryonic adaptations for life outside of water 0 Nearly all nonamniotes live in water 0 Adaptations to live on land while still providing for the needs 0 D Reproductive modes Oviparity Female lays the egg outside of her body and it develops outside of her body 0 Example are birds Ovoviviparity Female produces the egg and retains the egg inside her body during development 0 Egg hatches inside the female 0 Example are sharks 0 Almost like live births but not true live births Vivparity onytherian mammals Therefore Therian mammals show several reproduction modi cations 0 1 Loss of the egg shell 0 2 Reduction or loss of yolk egg secondarily microlecithal o Secondarily therians have an evolutionary history of macrolecithal ancestors but have a secondary modi cation 0 Still retains yolk sac o Trophoblast Embryology 11 metatherial egg 0 Ovum gets fertilized zygote then goes through cleavage o Earliest stage in humans is the blastocyst Inside the blastocyst is an aggregate of cells cell mass which gives rise to the embryo proper actual embryo Outside is the trophoblast sometimes called chorionicectoderm Lining of uterus is known as endometrium 0 When the blastocyst implants in the lining the trophoblast becomes the fetal contribution to the fetus essentially chorionic Embryonic or fetal contribution to the placenta Blood supply from fetus o The endometrium is the maternal contribution to the placenta Blood supply from the mother 0 Barrier between fetal and maternal blood contribution 0 Gas exchange etc o Amniotic uid creates aquatic environment still essentially unmodi ed in Metatheria o Placenta Allantois and yolk sac contribute to the umbilical chord o Allantois primarily functions in part to store uric acid but therians don t have uric acid primary form is urea which is water soluble This means Theria don t need uric acid storageremoval o Allantois also functions to vascularizes the Chorion Instead the Allantois is vascularizing the fetal contribution to the placenta blastocyst o Yolk sac connects to the developing gut vascularization of the vessels gut o Yolk sac does something else End up with a at embryo much like that of chicks Risks being preyed upon Modi cation of being preyed upon is being protected inside the mother 0 Live birth Eutheria even greater enhanced maternal care 0 Protection of the young Placenta afterbirth Amniotic membrane ruptures and the amniotic uid is released water breaks 0 Modes of Evolutionary o C Embryonic tissue interactions Eg changes in induction 0 One tissue causes another to differentiate in another way Such changes may explain the loss of teeth in modern birds 0 No teeth or vestige or reappearance O 0 Know Jurassic etc birds had teeth Normal tooth development 0 Oral epithelium inducesgt neural crest mesenchyme to formgt tooth germ inducesgt oral epithelium to form gt enamel organ 0 Two directions of induction reciprocal induction 0 Experiment with mouse neural crest and bird oral epithelium mesenchyme starts to differentiate into a tooth germ the mouse begins to form teeth then continuing the tooth germ sends signal to bird oral epithelium produces enamel around the mouse made dentin 0 Bird oral epithelium does rst job of inducing mouse neural crest mesenchyme 0 Oral epithelium does second job of enamel organ o Is capable of doing anything supposed to do if modern birds DID have teeth therefore has to be a step that s not working neural crest mesenchyme not responding to the inductive signal 0 Bird neural crest mesenchyme has lost the ability to respond to the signal 2nOI example of changes in tissue interactions 0 Changes in hormone action 0 Ex hip glands in voles mouselike Voles have hip glands that form in response to testosterone Glands absent in some species Could increase testosterone induce supernormal levels of testosterone with species without glands Result is glands form 0 There s been a change in tissue interaction Testosterone produced by endocrine glands precursor tissue isn t responsive to normal testosterone levels Don t know the adaptive basis 0 D Heterochrony evolutionary change in the timing of developmental events Different quotchronyquot time different timing of development in descendants than ancestors Changes in onset andor offset in a descendant in the production of organs or structures 0 Onsetoffset can look at an organ and determine when that organ starts to form onset nd out when organ stops developing offset 0 Ex heart forms earierin chicks than in frogs Onset occurs earlier in chicks interpret that as the derived state Chick heart would be larger because starts developing earlier so has more time heterochronic change 0 Frog endodermal cells packed with yolk nutrition o Yolk in developing chick is in the yolk sac endodermal cells don t have nutrition from the yolkso the yolk sac wall has to have vitelline vessels to create a blood ow to the endoderm D Heterochrony common mode for evolutionary change Functional reason need for access to yolk in chick yolk sac 0 Ex cessation of brain growth occurs laterin humans than in other apes As a result the descendant ontogeny continues longerthan in ancestral ontogeny Brain size would be bigger 0 Signi cant implications cognitive and communication abilities Plot brain size vs age shape and plateau s are both important picture 0 In other great apes offset occurs much earlier than in humans cessation of brain growth 0 Heterochronic change Slope of the curve is steeper in humans than other great apes o Slope also contributes to greater brain size Alometric change Each change is not mutually exclusive several things may occur to cause a modi cation 0 Ex Salamander axolotl Gills off the sides Eggs are laid in water most aquatic develop into larval aquatic and then metamorphose into terrestrial adults however axolotl doesn t metamorphose remains in larval stage even though adult able to reproduce etc 0 Example of paedomorphy o Offset of development is much earlier so early that metamorphism doesn t ever occur heterochrony Reproductive system continues to develop till maturity ie ancestral state of completion Why would this happen 0 Where it occurs is in desert habitats 0 There are standing bodies of water that are permanent which is better life than living terrestrially in the desert pays to be aquatic through their entire life if in desert if permanent standing bodies of water 0 There are some populations of the same species that metamorphose different environment 0 lnspecies variation with development clear that genetic based developmental changes can occur within species natural species with respect to development 0 E Pattern formation detailed analysis later on o The developmental establishment of precise complex spatial relationships between parts Like the bones of the arm and wrist 0 Can the establishment of such relationships be modi ed throughout descendants 0 Ex evolutionary transformation from reptilian to modern bird Hindlimb Two drawings pic Early in development the proximal and distal tarsals start to form as separate oglogin Start to form separately 0 Like in reptilian the proximal tarsals start to form separately but fuse with tibia tibiotarsus In birds unlike reptilian the metatarsals also fuse The distal tarsals fuse to the metatarsals tarsometatarsus 0 Joint between the two isn t the ankle it s known as intertarsa join No heel to the toe walk on their toes 0 Bird leg bends in the wrong direction they do have a knee 0 How did the bird leg come about The bula doesn t extend to the tarsals 0 That modi cation associated with the other modi cations 0 O O O O Lengthen the bula Simply by extending the bula can suppress the fusions characteristic of neornithes quotnew birdsquot Several fusion mechanisms are suppressed in the experimental animal Reconstructs what see in the limb of a bird First true bird is archaeopteryx Can reconstruct the ancestral bird Can see that the bula reduced in size and somehow that induced the fusing mechanisms The descendants the pattern offormation of the skeletal elements is modi ed in the development Not sure why fusions occur with short bula and not with longer 0 Have very long tarsometatarsus and tibiotarsus and joint in between Needed to get into ight requires a certain speed 0 Long bones are levered so the bird can jump with speed to get enough air speed to y 0 Adaptations to get into the air on takeoff 0 Bird has to stall to land controlled stall 0 Change angle of wind so no lift anymore start to fall 0 Cushion the blow by extending the really long legs 0 Plausible explanations F Reduction and loss 0 Vestige structure that is greatly reduced in descendant presumable has lost function Ex reduction of digits in horses horse handout in phylogeny o Atavism anomalous reappearance of lost structure in descendant As an anomaly reconstructing an ancestral stage Ex extra digits in horses 0 Once in awhile horse will have more than one fully formed digit 0 Modern horses retain the genetic and developmental processes of development of more than one toe so they must be suppressed and can reappear as an anomaly Ex openings that connect to the pharynx pharyngeal pouches evaginated but become pharyngeal slits to become gills in aquatic species programmed cell death is suppressed in tetrapods except larval amphibians As a pathology programmed cell death has been activated and pharyngeal slits occur no gills grow again 0 Humans retain the development program of programmed cell death the pathology tell us that but it s normally suppressed Importance reduction or loss may be required for evolution of new structures 0 Ex penguin wings Penguins are ightless wingpropelled divers Diving petrels Volant wingpropelled divers Shearwaters Volant not wingpropelled divers o Diving petrels to be a stage in between ightless and propelling in the water and ying and nonpropelling o Looked at 4 joints in all 3 types of birds and if any stiffening in the wings penguins had extremely stiff wings compared to diving petrels and shearwaters Diving petrels showed same widerange of movement as shearwaters For penguins to evolve the attened ipperlike wings penguins must have rst loss ight They couldn t evolve those attributes and still y 0 Must have lost ight before evolving the powerful ipper Loss of ight was a prerequisite for evolution of other attributes penguin ipperlike structure How to explain loss 0 What is the adaptive value of losing a structure 0 Why would it become reduced in size and eventually lost 0 1 Energetic savings save the energy and use it for something else 0 2 Noise squelch hypothesis 0 During development a structure no longer needed may noise developmentally that impinges other structures needed for function 0 Development might becomes noisy if descendant linages kept structures that aren t needed anymore 0 Don t want to get in the way of structures that are needed 0 G Evolutionary reversal Bledsoe says evolution is irreversible if something is lost isn t reverting back to ancestral state it s a further derived state 0 6 Origin of New Structures 0 A Principle of Continuity New structures evolve from preexisting structures 0 Modi ed existing structure 0 B Principle of integrated change when a structure changes structures associated with it may need to change as well When a structure evolves 0 Its parts change in an integrated manner 0 Under the control of localized developmental processes 0 Such that function is retained throughout Ex angiogenesis the developmental establishment of vasculature Localized developmental process triggered by some signal from tumor cells 0 6th Aortic arch is right next to the lung rudiment to vascularize it 0 Therefore when a structure evolves other structures must evolve as well so function is consistent Ex arthrogenesis the developmental process of joints 0 Sets of genes that work together to produce joints in particular circumstances triggered during normal development 0 Development of new joints 0 Double jaw jointed adaptation for chewing dentery and squamosal when they touch arthrogenesis is activated 0 They enlarged and touch 0 Allometric change could also be heterochronic 7 Homology and related concepts relational establishing relations between same part in different animals 0 Richard Owen 1843 quotthe organ is the same organ if in different animals under every variety of form and functionquot 0 A Homology in theory Homology is a relationship between structures in different taxa such that one is derived directly from the other or both are derived from the same precursor in their most recent common ancestor 0 Function is irrelevant with homology 0 Two organs can be similar and have different functions Endostyle amp thyroid Two structures may be similar anatomy and not homologous convergent evolution 0 Two structures may be dissimilar and still be homologous o B Homology in practice Three main criteria 0 Anatomical Ontogeny Fossil Record lntegumentary System 0 2 lntegumentary glands Ectodermal derivatives that form from epidermal epithelia 0 Form by invagination A Mucous glands adjective produce mucus noun which is mucigen plus water 0 Mucous is used to keep skin moist in salamanders etc o In shes present as unicellular glands O Exocrine glands ductless goblet cells protection from infection in shes o In amphibians present as multicellular glands o Synapomorphy of Tetrapoda further derived in Amniota Mucous glands are lost in amniotes a derived state Transformation series Unicellular gt multicellular gt loss of mucous glands o Amniotes are fully terrestrial B Poison glands involved in protection against predators ln shes and amphibians O Spine punctures predator and poison is injected 0 Absent in amniotes consider the loss of poison glands as a synapomorphy of Amniota O Monotremata mammals have poison could be an example of evolutionary reversal although he doesn t really believe in reversal but would have to do research C Oil glands produce thick oily secretions 0 Two general types 0 O Sebaceous glands produce sebum mammals only Oily skin Sebum gets onto the skin 0 Associated with hair follicles Primary function is to keep the epidermis and associated hair pliable so isn t dry Synapomorphy of Mammalia Uropygial gland produces a waxlike substance birds only Originally thought to be waterproo ng but some waterbirds have lost these glands could be an anti feather mite secretion Synapomorphy of Aves What are the homologies 0 Common ancestor in Amniota should have had some oil gland that was differentiated into sebaceous and Uropygial gland Fossil history Soft tissues don t fossilize well unlikely to get info from fossil record o W Form by invagination of the epidermal epithelia into underlying connective tissue but true of all integumentary glands Comparative anatomy Gross similarity 5ebaceous form from the walls of hair follicles o Essentially every hair has a sebaceous gland associated with it Uropygial Only one at base of the tail 0 Similar o Not much similarity Spatia similarity oNot similar only one at base of tail vs over integument Materia similarity Sebaceous oily secretion Uropygial waxlike substance 0 Similar 0 Basically no material similarity Histoogical similarity o Conclusion not homologous o Continuity new structures evolve from preexisting structures D Sweat glands unique to mammals 1 Eccrine watery secretions o Merocrine secretion exocytosis o Directly onto the free surface 0 Function thermoregulation 2 Apocrine associated with hair follicles o Apocrine tip of cells break off and release secretion o Secretion is a thicker scented secretion o Function pheromones communication Sexua function individual recognition function Scent plays a big role in sexual attraction o Located in groin and armpits o Secretions have bacterial ora associated with it and each person has slightly different E Mammary glands unique to mammals produce milk Theria breasts Monotremata don t have breasts speci cally but have the glands o 3 Keratinized structures A Stratum corneum and keratinization n tetrapods only thin in amphibians and thick in amniotes oThin stratum corneum is good for respiration through the skin o Thick for waterproo ng in terrestrial Transformation series no stratum corneum gt thin gt thick 0 Layer of dead cells packed with keratin o Basic adaptation for terrestrial existence oInvolves keratinization Free surface ces constantly wear away replaced by cells from stratum germinativum basal later in Craniates o Keratin is a mixture of many proteins Distinctive kind of bond disul de bonds Sistine thymine Keratinized structures are resistant to decaychanges Hair made up of keratins O 0 Change shape with heat breaks the disul de bonds and as the hair cools they reform in a different pattern than they were in before Change shape with chemicals 1 Soft keratins characteristic of hair 2 Hard keratins ngernails and toenails 39 B quotScalesquot called epidermal scales others are called bony scales 0 C Hair 0 O Occur in amniotes only Snakes lizards some mammals have epidermal scales Synapomorphy of Amniota l Structure lntegument 3 handout Hair shafts reside in hair follicles which have walls made of epidermis Apocrine sweat glands and sebaceous glands secrete products into the hair follicle Glands form by evagination of the hair follicle Hair root at bottom Germina matrix present in the hair root Where keratin is added as the hair is growing Cells of the hair root in the germinal matrix are active in mitotic cell division Extract DNA from hair if hair root is intact In the dermis underneath the hair root is the hairpapiIa dermis nerve endings provide nutrition from the capillaries to the hair root Wrapped around hair follicle itself are other nerve endings hairs are highly sensory Erector pili muscle Attaches to the wall of the follicle and to the basement membrane of the base of the epidermis Smooth muscle bers Associated with thermoregulation lndividual s cold bers of the erector pili muscle contract hair follicle becomes erect which increases the insulated layer so more air is trapped in the hair coat and the individual has an insulated layer lndividual s hot bers relax and the hair shafts all fall close to the free surface thin layer of air trapped little insulation and heat dissipates Secondary function Communicative function protection against others makes you look bigger Goosebumps can cause dimpling at the skin happens when cold andor when scared Hair is unique to mammals synapomorphy of Mammalia o Follicle forms by invagination an ingrowth of epidermis into dermis Sebaceous and apocrine glands evaginated off of the wall of the hair follicle 0 II Development 0 By ingrowth of somatic ectoderm into mesoderm 0 III Homologies of hair 0 Question is hair homologous to epidermal scales 0 Evidence Comparative anatomy Gross similarity hair vs scales hair consists of very ne shafts and scales don t not much gross similarity 0 Spatial similarity hair occurs allover on cats scales occur all over on reptiles general spatial similarity Material similarity scales made up of keratin hair is made up of keratin however speci c types differ some material similarity but only at super cial level of keratin Histological similarity Development scales form by folding and thickening of epidermis not by invagination of epidermis so not much histological similarity Fossil record not any fossil evidence 0 Weight of evidence points to NO homology Conclusion hair and epidermal scales are not homologous 0 Some have both hair and scales rats are the model Tails of rats have epidermal scales and hair vestigial but present Platelike scales thickening not folding like in snakes Hair is not coming out of the epidermal scales Spatial relationship each scale separated by a really thin piece of epidermis for movement hair grows out of this nvagination producing hair follicle between two adjacent epidermal scales 0 Hair homologous to the thin epidermal tissue between adjacent epidermal scales 0 Principle of continuity new structures exist from preexisting structure 0 Changed to 39new structures evolve from preexisting structures or tissues 0 4 Dermal specializations A Dermal armor eg osteostracans Basic structure on handout integument 4 o Platelike structures in the dermis armor 0 Two basic layers 1 denticulate layer shown by denticles outermost layer of dermal armor 2 nondenticulate layer vascular and laminar bone bone is the nondenticulate layer Vascular spaces inside the vascular bone that had bone marrow basal laminar layer with different histology than vascular layer Denticles surface most layer have an enamellike substance covering what histologically looks like den ne 0 Teeth tipoff that evolution of teeth is somehow involved with modi cation of dermal armor o Unclear what purpose was in jawless shes no big predators around to defend against may have been associated with calcium and phosphate metabolism no answer for sure They just know that it s the forerunner of remarkable set of modi cations of both denticulate and non denticulate layers 0 Components 0 Enamel covers denticles of denticulate layer 0 Dentine 0 Bone B Fish scales and other derivatives 0 5 Evolution of the lntegument o A Ancestral condition aquatic specializations earliest craniates Poison glands Mucous goblet cells adaptations for producing mucous on free surface probably protective against pathogens 0 B Early Tetrapoda transition to terrestrial life Amphibians two ways of life Larval aquatic stage and terrestrial adult stage frogs Example is the evolution of the stratum corneum Many amphibians use skin for respiration multicell mucous glands are also transition Retention of poison gland also adaptation only synapomorphy for craniata o C Amniota completely terrestrial skin Amniota have thick stratum corneum good for resisting desiccation associated is the loss of integumentary mucous glands no need for mucous glands in the skin 0 D Birds and mammals thermoregulation Endothermic Homeotherms A lot of heat and can control body temperature Mammals hair erector pili muscle Birds evolution of down feathers The Head Skeleton Part 1 Skeletal System 0 1 The skeletal system o A Supporting tissues Resist gravity and pull of muscle contraction Provide frame for the body 0 Works with muscular system skeletomuscular system 1 Notochord important embryonic function 2 Cartilage composed of chondrin collagenous bers in a gelatinous material 0 Biphasic material contributes to its strength Gelatinous made up of proteoglycans Basic structures 0 Perichondrium outside layer 0 quotPerlquot around quotChondriumquot Chondrin Around the Chondrin Fibrous layer Chondrogenic layer 0 Chondrin matrix with embedded bers 0 Chondrocytes in lacunae quotChondroquot Chondrin cartilage quotCytesquot cells Lacunae is a space Live cells in the cartilage Head skeleton 3 o Fibrous layer is the outside layer 0 Inner layer is chondrogenic Cells within are broblasts Fibroblasts differentiate into chondroblasts some lay down collagenous bers some differentiate into chondroblasts Differentiate into chondroblasts they secrete proteoglycans and get trapped in the matrix they re producing once trapped considered chondrocytes mature Each in lacunae space 0 Additional chondrin in the matrix 0 Living cells needs water waste removal gas exchange nutrition The chondrin matrix allows diffusion matrix from and to the perichondrium Primarily water isn t by diffusion just present in the chondrin matrix other parts are by diffusion The perichondrium there has to be a vascularsupply capillaries Types of cartilage o Hyaine quotclearquot Allows light to pass through it Characteristic of all craniate fetal skeletons The adult skeletal material for chondrichthyes 3 Bone Matrix consists of collagenous bers and hydroxyapatite mineral form of calcium phosphate cartilage has calcium carbonate Highly vascular mineralized matrix of collagenous bers in hydroxyapatite o Biphasic material Basic structure of Haversian bone 0 Sometimes known as cartilage replacement bone 0 Periosteum on the outside quotsteumquot bone 0 Skeleton is paedomorphic o Retain the fetal skeleton into adulthood Characteristic of many joints in the body 0 Not all joints have hyaline cartilage Eastic characteristic of deformation and returning to formation Pinnae external ear of animals springs back Elastic bers are characteristic of elastic cartilage Epiglottis ap of cartilage Fibrocartiage Perichondrium is dense with collagenous bers Innervertebral disks Calci ed embedded with calcium carbonate typically Very hard cartilage Cartilage of the jaws of sharks Connective tissue layer surrounding the bone Outer brous layer lnner osteogenic layer 0 Basic structure of bone is like basic structure of cartilage 0 Endosteum Connective tissue on the marrow cavity side Haversian systems osteons cartilage replacement bone 0 O O O Haversian canal vascular canal Bone matrix does not permit diffusion like in cartilage Osteocytes in lacunae Canaliculi contain osteocyte cytoplasmic processes Tiny canals that run from the lacunae to Haversian canal Permit exchange of material between osteocytes and Haversian canal Handout head skeleton 4 o Crosssection of an osteon Center of concentric ring is the vascular space Haversian canal Bone matrix and lamellae layers and within the layers there are lacunae o Osteons interlock in a mechanical way Dermal bone trabeculae surrounded by layers of bone 0 No cartilage precursor for this kind of bone o Trabecula any strutlike structure 0 Handout head skeleton 3 Dermal bones are typically at Series of struts in between are spaces containing bone marrow Layers of bone on margin of at bone 0 B Strength of tissues Supporting tissues resisttension compression shear and torsion Torsion twisting Breaking strength lbin2 Tension Compression Shear Steel 130000 120000 50000 Concrete 300 3000 40x weaker than steel Bone 18000 24000 7000 Stronger than concrete Cartilage 2000 4000 Tendons 10000 Bone is biphasic high tensile strength collagenous bers bone is a composite o C Cartilage formation Fibroblasts gt chondroblasts gt chondrocytes Two types of cartilage growth Interstitial growth production of chondrin between adjacent chondrocytes o Handout head skeleton 3 Fibroblasts differentiate into chondroblasts and get caught as chondrocytes and are active wall of cartilage between adjacent chondrocytes Strength inside piece of cartilage o Appositiona growth growth at the margin of the growing block of cartilage o Handout Chondroblasts lay down matrix at margin of existing margin increases size of growing cartilage o D Bone development Osteogenesis of the two main developmental types 0 1 Cartilage replacement bone 0 A model of cartilage is produced and that model then is destroyed as bone replaces the chondrin matrix o Basic pattern Mesenchyme gt broblasts gt cartilage gt bone quotCartilage modelquot is replaced by bone 0 Details Chondrocasts destroy the chondrin Go through and quoteatquot the chondrin as go along Osteoblasts lay down bone matrix in canal formed by chondroclasts precursor to Haversian Canal vascular space Tunnel cells come in and lay down bone in the tunnel Layers of bone within Osteoblasts become trapped in lacunae mature as osteocytes Blasts are immature that mature Cytes when caught in matrix that they secrete Osteocytes participate in gas exchange and nutrients etc through canaliculi which have cytoplasmic process 0 When osteocytes get trapped must start to form canaliculi On one side of osteocyte cell secretes hydrochloric acid which dissolves a small piece of bone and extends canaliculi into space and continues with more Cytes Blood vessels from the perichondrium grow into the Haversian canal o Arbitrary if called Periosteum or perichondrium at this stage Osteoclasts destroy part of the older Haversian system A new Haversian system forms replacing the destroyed part Haversian systems thus interconnect Handout head skeleton 4 Crosssection of osteon 0 Old bone 0 Chondrin matrix 0 Osteoclasts already started to destroy old bone 0 Vascular space has blood vessel running through Bone lamellae are layers 0 Wave of osteoblasts that create layer 1 another wave creates layer 2 up to 4th wave creates bone with 4 bone lamellae O o Osteoblasts and osteoclasts remodel bone based on stresses Space missions if don t exercise the stresses on the bone are different than in gravity environment seriously weakens the bones especially hip bone Longterm bed rest restriction from movements there aren t forces associated with laying down seriously weakens the bones especially hip bone Maintenance of bones under normal forces 0 2 lntramembranous bone dermal bone 0 Basic pattern Mesenchyme gt bone Critical part no cartilage as precursor Chondricthian shes lackthis type of bone dermal o Details Mesenchyme proliferates Cells deposit collagenous bers 0 Cell type is broblasts Ground substance is secreted also by broblasts Bone matrix is deposited around bers to yield trabeculae Osteoblasts to osteoclasts same thing but without cartilage Trabeculae coalesce Layers of bone are deposited on periphery yielding at bone 0 End up with structure on head skeleton 3 trabeculae marrow cavities layers of bone classic example of dermal bone 0 E Bone Growth pp 189192 and Figs 511 and 512 Cartilage replacement bone bone forms in the middle of the cartilage model at the diaphysis Hyaline and calci ed cartilage Cartilage continues to grow at the model ends the epiphyses Later bone centers form in the epiphyses Bone at center and at the end and a plate of cartilage in between epiphyseal plate Resulting epiphyseal plate cartilage continues to grow 0 As it continues to grow new cartilage will be replaced by bone but epiphyseal plate lingers so bone elongates until calci cation stops and bone stops growing Bone is added underneath the Periosteum causes increase in girth Calci ed cartilage is hard Handout skeleton 5 o F Joints Synarthroses o Joints with little or no movement 0 Suture joints in the head Diarthroses synovial joints Knee elbow joint 0 Pp 193194 know gure 514 Handout skeleton 6 0 Big difference between skeletons is the intramembranous ossi cation is characteristic of integumentary no cartilage replacement and most of the endoskeleton is cartilage replacement 0 Most of cranial is neural crest Endoskeleton o Somatic axial and appendicular o Visceral pharyngeal Skeletal elements of pharyngeal arches between pharyngeal pouches Mandibular jaw and elementary precursors Hyoid Brachial arches gill arches in sharks 0 Support the wall of pharynx from which gills grow 0 5 15 pharyngeal arches 37 Head skeleton part 2 skull jaws and other arch derivatives 0 1 Cephaization craniates posses a distinct head region head end is elaborated anatomically evolutionarily developmentally functionally etc Braincase Tripartite brain Associated sensory pacodes Neural crest Other structures 0 Craniates are cephalized In association with other synampomorphies eg muscularization of the hypomere Lateral plate mesoderm two layers somatic lateral and splanchnic medial o Splanchnic gives rise to layers of the guts which are heavy increase in feeding rate in craniates increased processing modi cations in head which increases feeding rate 0 2 Components of the Skull 0 A Chondrocranium Mainly from neural crest plus a small amount of mesodermal mesenchyme Ossi es via cartilage replacement A component of the axial division of the endoskeleton Consists of the braincase and sense capsules Begins as separate cartilage elements Parachordas 2 on the caudal oor of developing chondrocranial Trabecuae located on rostral oor Occipita arch very back forms the caudal wall single arch o Foramen magnum hole in the cartilage Sense capsules o Nasal capsule rostralmost In most craniates mostly a pair lamprey s only have one o Orbital cartilage Left and right Form the walls of the orbits places where lateral eyes develop 0 Shark 0 Otic capsule caudalmost Paired in alcraniates The otic capsules expand and fuse to occipital arch The trabeculae and parachordals will expand and form oor They all fuse together 0 B Dermatocranium Mainly from mesodermal mesenchyme by intramembranous ossi cation Part of anterior portion is of neural crest origin Part of the integumentary skeleton Modi ed dermal bone with no cartilage precursor Consists of the super cial sheathing bones of the skull including secondary jaws and roof of braincase Chondricthian shes do not have a dermatocranium Dense connective tissues covers the roof instead completing the braincase o C Splanchnocranium The visceral skeleton skeletal elements of the pharyngeal arches From neural crest via cartilage replacement Has been modi ed in important ways 0 Ancestrally brachial gill arches o Earliest craniates jawless shes all of the arches were unmodi ed o Derived modi cations 0 Mandibular arch gt primary jaws Palato upper neckles lower Gnathostomata jaws open Hyoid archgt jaw supports Don t have a name for the clade delimited by jaw supports placoderms had jaws but no hyoid arch jaw supports further modi ed gt stapes Bone of inner ear apparatus Synapomorphy of Tetrapoda jaw joint elements gt other inner ear ossicles Posterior brachial arches gt support for tongue and larynx 2 developmental elements chondrocranium and splanchnopleure O O 00 o D Integration Skull conjoins the 3 components That is the 3 elements fuse developmentally 3 Evolution of the skull o A Ancestral craniate condition drawing 0 B Primary jaws First kind of jaws earliest jaws of Craniata Gnathostomata Hypothesis primary jaws evolved from a brachial arch mandibular bottom jaw arch Epibrachial cartilage of mandibular arch became the palatoquadrate upperjaw Ceratobrachial cartilage became Meckel s cartilage Iowerjaw Evidence of statements of homology 0 Comparative anatomy o jaws lie at the start of a series of gill arches similar to them in shape and position skeletal Spatial similarity and gross similarity shape 0 jaw muscles are in form and position like gill arch muscles muscular Unmodi ed muscle called adductor which bers run between epi and ceratobrachial The position of mandibular adductor is similar to unmodi ed arches o Nerves ofjaw muscles arise form brain in pattern like those of muscles of gill arches nervous 0 Developmental anatomy embryology o Skeletal elements of the jaw develop from neural crest not from mesoderm predict in hypothesis 0 Fossil record 0 Count the number of brachial arches in a jawless sh and count the number of brachial arches in Acanthodian there should be one fewer unmodi ed brachial arch because mandibular arch modi ed into jaw this is what we see one less unmodi ed arch The numbers correlate Absence of homologue supports hypothesis 0 C Hyomandibula hyoid arch modi cation associated with jaw elements Derived condition hyoid arch modi ed into jaw brace Speci cally epihyal modi ed into hyomandibula o Epibrachial cartilage of the hyoid arch o 2 fewer unmodi ed arches in sharks Delimits clades Chondrichthyes and Pulmovertebrata o D Secondary jaw elements modi cations of the primary jaw Two main modi cations 0 1 Reduction of the primary jaw elements 0 Palatoquadrate reduced except for posteriorly the guadrate o Meckel s cartilage is reduced except for posteriorly the m o The jaw joint is between the quadrate and the articular o Vestigial what replaces them Dermatocranium enlarges and replaces o 2 Enlargement and addition of dermatocranial elements onto the primary jaw elements 0 2 bones are added to the palatoquadrate maxilla and premaxilla o Dentary angular and other postdentary elements are added to Meckel s cartilage Important point in secondary jaw jaw joint between palatoquadrate and Meckel s cartilage is retained Quadrate will become incus of mammalian middle ear Articular is precursor of malleus o E Stapes and tympanic membrane synampomorphies of Tetrapoda associated with evolution of middle ear apparatus Fish s use lateral line to detect waterborne vibrations Airborne vibrations are lower Tetrapods needed evolution of inner ear to detect airborne vibrations The hypomandibula became the stapes a middle ear bone The spiracular gill cleft became the middle ear cavity and Eustachian tube The embryonic closing plate retained intact into adult to yield tympanic membrane 0 F The mammalian condition The Head Skeleton Part 3 Mammalian jaw Apparatus and Middle Ear 1 Introduction 0 Mammals are distinctive Further cephalized elaborations also associated with physiological adaptation warmblooded endothermic Endothermic also homoeothermic Generate substantial amounts of metabolic heat 0 Have to have a higher food intake Associate novelties Facial musculature associated with chewing Lips associated with manipulation of food and communication Cheeks also associated with manipulation of food and communication Heterodont dentition regionalized teeth teeth of different shapes 0 Modi ed jaw muscles 0 Large muscular tongue movement of food within oral cavity and comm Secondary palate soft palate extends back into pharynx and displaces nostrils to right next to the trachea mammals can breathe while chewing All associated with evolution of endothermy These are involved in chewing o A Condition ancestral to mammals quotReptilianquot condition 0 1 middle ear ossicle Stapes Quadratearticularjawjoint 0 Multiple bones in the lowerjaw o Articular is retained in lowerjaw o B Dentary squamosal joint Novel jaw joint Replaces ancestral joint ancestral joint is the quadrate articular joint 0 What happened to the ancestral structures 0 C Malleus incus stapes and tympanic bone Homologies from comparative anatomy 0 Connection between pharynx and inner ear Eustachian tube 0 Malleus lncus Stapes Hypotheses of homologyHomologies from comparative anatomy quotReptilianquot Mammalian Sta pes Sta pes Quadrate jaw joint between quadrate and lncus small middle ear oscillate articulate Articular Malleus synapomorphy of Mammalia with incus amp tympanic bone Angular Tympanic bone another new middle ear bone Handout Head skeleton 15 Vibrations through external cause malleus to vibrate since tympanic is articulating it also vibrates causing the incus to vibrate act as levers to transduce the vibrations then stapes vibrates causing inner ear uids to vibrate Tympanic bone resides on edge of most of the tympanic membrane acts as support to the membrane Embryology and fossil record provide congruent evidence Handout head skeleton 16 o Embryology Apoptosis turned on in humans causing elements to separate from what see in Metatherian condition jaw joint between Dentury and squamosal o Synovial joint localized developmental production arthrogenesis 0 Not a new jaw joint but the touching of Dentury and squamosal activates development of the joint 0 Fossil Record Probainognathus had a secondary joint Articulation between squamosal and jaw joint Free up quadrate and articular to separate and articulate at inner ear 0 Critical intermediate stage precursor to the further changes seen developmentally o D Transitional Forms allow to ll in the transformation series Many known Show a graded series of changes Gradual change from what saw in Probainognathus than what see now 0 Basic idea is that there are gradual changes that progressively improve jaw and ear function 0 These forms would all have to exist in a type of environment that was stable 0 Don t know everything about the story Ex Double jaw joint in Probainognathus 0 Key points 1 Continuity new structures evolve from preexisting structures 2 Integrated change transitional forms were fully functional 0 As a structure evolves its associated structures change under localized process in that function is retained through modi cation 0 Or else would go extinct 3 Enlargement via increase in growth rates of the Dentury and squamosal Allometric changes Malleus and incus are really small quadrate and articulate are large in nonmammals so decrease in growth rates of malleus and incus Allometric changes 4 New joint via arthrogenesis the two bones touched during development 5 Programmed cell death 0 E Adaptive Scenario Endothermy when you re ectothermic you have to bask in the sun to heat up by laying out there is a greater chance of predation Chewing facilitates rapid processing of food 0 Dentury squamosal jaw joint Facilitates chewing Escape from predators inner ear apparatus 0 Earliest mammals were probably nocturnal Dinosaurs were around 0 No light so use hearing excellent hearing 0 Also enhanced prey capture 0 2 Summary of Head Skeleton Evolution 0 Handout 17 amp 18 The Axial Skeleton One of the two basic components of somatic endoskeleton Provides frame for body resists pull of gravity and muscle contraction 1 Components 0 Chondrocranium o Vertebral Column 0 Ribs o Sternum 2 Structure 0 Centrum main part 0 Prezygapophysis o Postzygapophysis caudal articular process o Neural arch dorsal part of the centrum Associated with it is the neural canal through which spinal chord passes o Spinous processes back muscle attachment 0 Transverse processes laterally Handout Axial Skeleton 3 o Tetrapods 0 Fish Dorsal most is the spinous process back Laterally two transverse processes left and right rib attachment in tetrapods Zygapophysis pre and post pre is also known as cranial articular processes Adjacent vertebrae from lateral prospective Centrum largest part of each vertebrae lntervertebral disk between two adjacent centrum brous cartilage o quotRuptured diskquot Pre and post zyga articulate 0 Also the centrum and intervertebral disk articulate Post zyga most cranial articulates with the most caudal of pre zyga Transverse processes point out at you from a point on sheet and behind screen Spinal chord lntervertebral foramen spinal chord passes through that as well 0 The spinal nerves pass through each intervertebral foramen out at you left and behind the screen right 0 Most nerves pass down the intervertebral disk No transverse processes ribs articulate at basipophysis small processes 2Vertebrae o A Structure Centrum l Transverse processes previous Trunk vertebrae differ from caudal vertebrae Caudal vertebrae have hemal arch Spinal chord passes through neural arch caudal arteries and veins through hemal arch Handout Axial Skeleton 3 0 Second arch ventrally on sh quotHemoquot hemoglobin o Arteries and veins of the tail passing through the hemal arch o B Function Fishes mainly as antishortening device Sharks myomeres are essential for locomotion 0 Contract in a wave that s slightly delayed in time on either side 0 Caudal n moves left and right o If vertebral column weren t there there wouldn t be a frame in which the two waves could function Tetrapods acts to support the body against gravity at least nonlarval Lissamphibia plus Amniota o C Development Vertebrae develop from schlerotome some mesenchyme 3 Vertebral Regionalization o Ancestrally two basic regions trunk and caudal vertebrae o Tetrapods shes retain the craniate condition of the two basic regions Trunk quotAmphibiansquot Lissamphibia o Cervical 1 just caudal to the back of the skull neck 0 Trunk many basically like the tetrapod condition on axial skel 3 o Sacral 1 lower back 0 Most tetrapods are terrestrial head is supported by buoyancy in water so the cervical vertebrae supports the head modi ed vertebrae for head support on land 0 Salamanders run sidetoside like shes do sacral vertebrae o Amniotes o Cervical 2 head support and movement 0 Thoracic quotribbearing support ribcage and are located at level of pectoral girdles o Lumbar level of lower back 0 Sacral 2 level of pelvic girdle 0 Associated with this is a change in gate amniotes have limbs moving underneath the trunk don t have a splayed out pattern like Lissamphibia Caudal quotAmphibiansquot frogs as example 0 Urostyle anurans clade of frogs Adult frogs hop large back legs Caudal vertebrae are fused in a rodlike structure Hip bones project a bit caudally on either side of the Urostyle extended pair of rods Surface area for attachment of big muscles of the leg for hopping o Caudal standard caudal vertebrae not modi ed 0 Amniotes 0 Birds Pygostyle Consists of 5 fused distal caudal vertebrae single bone 0 Proximal caudal vertebra are free Pygostyle important because that s where the tail feathers connect dense connective tissue Connects the ight feathers of the tail to the trunk o Humans Coccyx tailbone 35 fused vestigial caudal vertebrae o Caudal unmodi ed or notparticularly elaborated Most amniotes o Handout axial skeleton 4 Humans also have 7 cervical First two cervical vertebrae are elaborated o 1 Atlas 0 2 Axis modi ed to allow head rotation Rest of them are not species Humans have 12 cats have 13 Thoracic vertebrae Ribs of ribcage articulate with Scapula is at level of several proximal thoracic Lumbar 7 in cats 5 in humans Sacral fused into sacrum humans too 0 3 sacral vertebrae Caudal between 21 and 23 caudal vertebrae in tail humans don t Appendicular Skeleton 1 Introduction 0 Synapomorphy of Gnathostomata o Skeletal elements of the paired appendages and associated girdles 0 Associated with locomotion that s not associated with jawless shes o Paired ns in Gnathostomata paired limbs in Tetrapoda 2 Structure and function 0 Chondrichthyes Paired pectoral ns 0 Just caudal to the skull Paired pelvic ns Paired hind ns Associated pectoral and pelvic girdles Support the paired ns Fins are narrowbased stiff and xed in area Functions for stability and some turning Caudal n provides locomotive forces 0 Actinopterygii and Sarcopterygii Ray nned shes have ray ns 0 Skeletal elements known as n rays that support the ns 0 Muscles associated with that cause the area of the n to change Pectoral and pelvic ns can change area Fin rays are moveable For propulsion turning braking 0 Not stability 0 Stabilized by modi ed lungs as swim bladders Pulmovertebrata Swim bladder functions as stabilizer Lobed ns synapomorphy of Sarcopterygii Fins eshy have enlarged base 0 One group rhipidistians has asymmetric n axes o Tipoff that limbs have evolved from ns speci cally lobed ns 0 Asymmetric aspect also characteristic of Tetrapoda o Tetrapods Handout appendicular skeleton 3 0 Basic pattern in forelimb and Hindlimb are the same serial homology different elements within a single individual have correspondence which suggest duplication ancestrally of structure 0 Axial skeleton serial homology vertebral column 0 3 Limb development 0 A The limb bud left and right fore left and right hind Forms from mesenchyme aggregating laterally Mesenchyme is from myotomic buds of somites and the somatic layer of the hypomere lateral plate 0 Mesodermal mesenchyme Somites haven t differentiated yet myotomic bud outgrowth cells migrate laterally mesenchyme also comes from somatic layer of the lateral plate 0 B Apical ectodermal ridge AER o Induced to form by the migrating mesenchyme of the limb bud Area at the tip of the limb bud Essential for proliferation of the mesenchyme limb outgrowth o Limb speci city resides in the mesenchyme notin the ectoderm speci city between the hindand fore Leg mesoderm wing ectoderm gt leg Wing mesoderm leg ectoderm gt wing o C Chondrogenesis Cartilage is going to form and ossify by cartilage replacement Condensation Mesenchyme aggregates Elongation o Aggregation restricted to proximodistal axis by perichondrium Hence primary axis elongates Branching Primary axis branches to yield cranial and caudal axes Cranial axis ceases to branch Caudal axis continues to branch Handout Appendicular 5 o Aggregating mesenchymal cells 0 Perichondrium continues to form and restricts elongation at proximodistal axis 0 Segmentation where you get apoptosis at certain regions of developing limb o D Pattern Formation The establishment of precise spatial relationships between parts during development Handout Appendicular 6 the basic pattern 0 E Zone of polarizing activity ZPA A region on the caudal margin of the developing limb bud Establishes a morphogen gradient Secrete the substance and it dissipates down the limb bud but there is more concentration on the caudal end than reaches the cranial end As a result caudal axis continues to branch and cranial axis does not Experimental evidence back of Appendicular 6 o F ShubinAlberch model handout Appendicular 7 2 sources of skeletonizing mesenchyme mytomic buds of somites also from somatic layer of lateral plate Skeletonizing mesenchyme Primary axis Condenses and elongates to form primary axis Undergoes branching into RadiusTibia amp Ulna Fibula 0 Under control of ZPA morphogen that diffuses from Caudal to Cranial o Caudal continues to branch Bends cranial As bends creates carpals or tarsals longer are meta Somatic induced to create AER which continues to produced by mesenchyme to maintain AER maintenance factor AER sends signal to mesenchyme to keep proliferating reciprocal induction LM loose mesenchyme some for muscles Digit numbers last one to form is digit 1 rst one to form is digit 5 Metacarpalsmetatarsals continue to elongate and produce phalanges segmentations between developing meta and phalanges of digits 0 Typically apoptosis causing webbing of forming digits to regress digits are separate 0 Each forming digit at tip needs a piece of AER to continue outgrowth of digits as phalanges of digits are forming AER is split by apoptosis 0 D4 forms before the other meta form because of branching 4 Early tetrapods o A The shtetrapod transition Back of Appendicular 7 o B The origin of the digital arch the new structure Handout Appendicular 7 Homologues in Eusthanopteron correspondence in details and shapes of proximal elements 0 quotPrelimbquot 0 Digital arch is new how exactly does digital arch form Modi cation of development look at zebra sh as ancestor to Tetrapoda Earliest stage that can see limb bud ancestral zone of Hox gene expression another zone of Hox gene at the tip of the developing limb bud new zone 0 Localized at the level of the digital arch 0 Important zone for converting tissue so it forms skeletal elements Propose that the digital arch is a modi cation homologous to tissue at the tip of the developing limb bud 0 New structure evolves from a preexisting tissue 0 C Homology revisited Use the pattern of the developmental stages in making assessments of homologies Similar developmental processes were coopted in similar ways drosophila eye and human eye not that they are homologous o D The role of Hox genes in limb evolution 0 5 Loss of digits in modern tetrapods 0 Extra mesenchyme in developing arch maybe amount of mesenchyme is controlling the number of digits 0 Another offset of observations handout 7 The last digit to form is digit 1 thumb big toe Digit identity the last digit to form is typically the rst digit to be lost evolutionarily Number of mesenchyme is controlling the number of digits 0 When digits are lost there is less mesenchyme in the digital arch Amount of mesenchyme is controlling how many digits form 0 No gene for any single digit 0 Localized developmental processes can be activated so amount of mesenchyme is being altered in evolutionary sense translating into more or less digits Could lead to heterochronic change Propose that small alterations of timing of expression or repression of Hox genes may be associated with total amount of mesenchyme The Muscular System 0 1 Muscle tissues 0 Essential to many functions Locomotion and posture Circulation Thermoregulation erector pili Secretion multicellular exocrine glands Digestion o A Contractility Unique 0 Muscle bers can shorter or have tension produced lsotonic contraction Muscle shortens o lnsertion is drawn toward origin 0 Origin is point of muscle attachment that does not move during contraction o Insertion is that point of muscular attachment that does move during contraction Example biceps point that attaches is at shoulder which doesn t move but the insertion moves closer to Humerus when contraction occurs 0 Movement occurs Isometric contraction Opposing force prevents shortening Tension is produced in the muscle 0 Provides postural support Synergists muscles with same action Antagonists muscles with opposite action Biceps and triceps o B Types of muscle tissue Smooth Skeletal Cardiac See and know the histology handout o 2 Muscle groups and their innervation innervation nerve supply 0 A Somatic musculature Develops from myotomes somitomeres and somatic layer of hypomere Myotomes are regions of somites Somitomeres are regions of head mesoderm Somatic layer of hypomere is one of the two parts of lateral plate Histology skeletal lnnervated by somatic neurons Adjusts organism to external environment Re exes Major groups follow skeletal groups 0 Axial muscles Appendicular muscles 0 B Visceral musculature Develops from splanchnic layer of hypomere Histology smooth or cardiac Gut layer smooth 0 Heart cardiac lnnervated by visceral motor neurons Adjust internal environment Myocardium of the heart heart changes rate of beating depending in internal situations Maintaining homeostasis 3 Embryonic development 0 Musculature is derived from various regions of mesoderm one exception intrinsic muscles of the iris which are ectodermal o Crucial to understanding the musculature is understanding its innervation Integrating skeleto musculo neuro systems 0 A Somatic muscles Handout 3 o B Visceral muscles Develop from splanchnic layer of hypomere Muscles of the gut wall and heart lnnervated by visceral motor neurons 4 Basic Craniate Pattern o A Extrinsic ocular muscles Muscles that rotate the eyeball Consist of o 4 rectus muscles 0 Dorsal Rectus o Ventral o Medial 0 Lateral 2 Oblique muscles 0 Dorsal o Ventral Group innervated by cranial nerves 3 4 amp 6 Cause movement of eyeball o B Branchiomeric muscles quotbranchioquot pharyngeal arches quotmericquot segmentsseries Pharyngeal arch muscles Compress pharynx and branchial chambers Respiration feeding Antagonists hypobranchials Crucial component mandibular arch musculature innervated by cranial nerve 5 Muscles of the jaws including M adductor mandibulae a jaw closer o M Adductor man is a synapomorphy of Gnathostomata because ofjaws Handout 5 C Epibrachial and hypobrachial muscles NOT Branchiomeric which are associated with the series of muscles Epibrachial Dorsal to gill region Segmented Function in head movement 0 lnnervated by dorsal rami of spinal nerves occipital nerves Hypobrachial o Ventral to gill region Extend forward and attach to the pharyngeal arches Open mouth and expand pharynx o The Branchiomeric open and compress the hypobrachial close and expand the mouth antagonists o lnnervated by the united ventral rami of spinal nerves occipital Develop from occipital myotome o Nerve called the hypobrachial nerve in shes o Becomes hypogossacranial nerve 12 in Amniotes Amniotes have expanded occipital region to incorporate part of ancestral spinal chord becomes part of the brain hypobrachial nerve is now a cranial nerve o D Trunk tail and appendicular muscles Trunk and tail ancestrally within craniata Myomeres segmented axial musculature o Divided into dorsal epaxial and ventral hypaxial components Handout 5 0 Function in sidetoside bending hence propulsion Appendicular synapomorphy of Gnathostomata paired ns 0 Simple in shes Above n single dorsal abductor levator move from the trunk Below n single ventral adductor depressor move to the trunk 0 Functions primarily in stability ancestrally in Tetrapoda and propulsion in some shes Highly modi ed in Tetrapoda 5 Evolution of the Musculature early tetrapods and mammals o A Retractor bulbTetrapod synapomorphy mammals don t have Water cleans eyeball in shes but the air dries out and brings dust into the eye developed the Nictitating membrane 0 Corner of the eye 0 Functions to ash over the eye to moisten and clean surface of the eye Slightly pulls the eye into the orbit so the Nictitating membrane sweeps over and cleans the eyeball o B Branchiomeric muscles M Depressor mandibulae Has evolved from hyoid arch musculature branchiomeric Depresses the mandibula a neraw depressor Tetrapod synapomorphy o Hypobrachial were modi ed for tongue support so needed a new jaw depressor Lost in mammals replaced by M Digastricus quot2 belliesquot 0 Part of the mandibular arch anteriorly trigeminal V 0 Part of the hyoid arch posteriorly facial Vll Pattern of innervation to infer developmental process M Adductor mandibulae o Gnathostomata synapomorphy Ancestrally a large jaw closer Associated with mandibular arch trigeminal V o In mammals divides into three parts 0 M Temporalis o M Masseter o M Pterygoideus These muscles are associated with evolution of chewing like denturysquamousal joint Middle ear muscles in mammals Malleus has M tensor tympani attached to it 0 Origin is on the Malleus insertion on the tympanic membrane 0 When contracts tightens the tympanic membrane 0 Every time loud noise even in speech general external it will contract re exively to protect the tympanic membrane Articular from MC from ceratobranchial from mandibular arch From Mandibular arch musculature trigeminal 5 Hearing and protection Stapes has M stapedius o Synapomorphy of Tetrapoda From Hyoid arch musculature facial Vll Stapes modi ed from hyomandibula which is innervated by VII 0 Tiny histology is skeletal control involuntary 0 Also true for M tensor tympani Dampens excessive vibrations like tympani o Prevents damage in face of loud sounds Important pointquot ancestral patterns between skeleton muscles and nerves are retained Function is being maintained throughout Corollary of principle of integrated change Facial muscles 0 Unique to mammals o Mammals are only ones who have faces musculature is complex Enlarged hyoid arch elements 0 lnnervated by Vll facial Functions chewing communication 0 C Hypobranchial muscles Occipital myotomes innervated by hypobranchial nerve Become more complex in tetrapods for tongue movement In mammals they yield M lingualis chewing vocalization lnnervated by hypoglossal Xll synapomorphy of Amniota Back of head 0 D Trunk muscles Trend toward fusion of segments Body wall divides into three layers 0 External oblique Internal oblique Transverse abdominus See in shes the trend toward fusion of segments New strip added not present in shes New midventral strip is added rectus abdominus Tetrapoda o E Appendicular muscles 0 Simple within Gnathostomata single adductor and abductor Elaborated dorsal or ventral muscle masses of sh ns 0 F Signi cance of mammalian modi cations Mammalian Synapomorphies M digastricus o Cranial nerve Vll facial hyoid musculature Opening mouth lowering jaw chewing M temporalis masseter and pterygoideus o Evolved from mandibular arch musculature V trigeminal Chewing Facial musculature o Hyoid arch musculature Vll facial Chewing M tensor tympani o Mandibular arch musculature V trigeminal Hearing M lingualis o Hypobranchial Xll hypoglossal Chewing Mammals have their head musculature modi ed for chewing hearing chewing associated with novel mammalian dentarysquamousal joint 0 Function carries throughout THE SENSE ORGANS 0 Response to external or internal stimulus central nervous system integrates ac on 1 Introduction 0 A Classi cation by location Exteroceptors Typically onnear surface integument of animal 0 Receive external stimuli Ex eyes inner ear Proprioceptors Specialized nerve endings that wrap around muscles and report positionlocation and tension of muscles 0 Providing information about conditions internally Enteroceptors Sense organs internally other than proprioceptors Sense organs in the gut that provide info about occurring in gut Myocardium of the heart 0 Transmitting stimuli to CNS on what s happening internally o B Classi cation by stimulus Mechanoreceptors 0 Ex middle and inner ear 0 Respond to waves of pressure Radioreceptors Receive electromagnetic radiation 0 Ex lateral eyes light is form of electromagnetic radiation Chemoreceptors Sensitive to chemical stimuli Ex smell taste 2 The Olfactory Sense 0 Responsive to chemicals 0 Highly sensitive Sensitivity depends on the chemical o Sensory cells send signals directly to the brain Functionally to the forebrain o Modi ed neurons Have axons Their axons form cranial nerve 1 the olfactory nerve A Olfactory epithelium Olfactory cells Nonmotile cilia quotolfactory hairsquot on free surface side 0 Cell body within strati ed epithelium o Axons penetrate the underlying connective tissue to form cranial nerve 1 Supporting cells nonsensory Basal cells attach to the basement membrane Handout 3 0 Substance lands on the nonmotile cilia causing depolarization which travels down the axon Basal most basal cells attach to basement membrane Axon will penetrate underlying connective tissue 0 B Olfactory sacs From olfactory placodes via invagination from skin somatic ectoderm Lined with olfactory epithelium Epithelium folded into olfactory lamellae Platelike but not hard Chemoreception is surface area increase amount of surface area so fold Open to external world via nares Handout 3 o In most craniates they re paired 0 Wall folded to increase surface area black is olfactory epithelium o Dots are naris in shes water comes into the olfactory sacs and the epithelium senses chemicals and the water goes out the same way came in blindended Connect to oral cavity in lung shes and tetrapods 0 True in humans as well 0 The nares choanae OO o Synapomorphy of Rhipidistia Spend a lot of time out of water tetrapods These organisms are experiencing a lot of air 0 Causes air to be brought into the olfactory sacs and through the nasal passages passing over olfactory epithelium causing smell 0 C Vomeronasal organ Accessory chemical sense present in oral cavity Complex and not well understood Snakes distance sensing On the roof of the oral cavity 0 Distance tasting organ 0 Stick tongue out and retract into oral cavity canvas chemical environment in atmosphere in front of the snout chemicals get on the tongue and stick tongue into nasal cavity Think modi cation of olfactory sacs 0 Evidence innervation lnnervated by branches of cranial nerve l olfactory 3 Taste gustatory sense 0 Located in the oral epithelium taste quotbudsquot 0 Each really a taste pore develops from endodermal cells Handout 3 0 Less sensitive than smell responds only to sweet sour salty and bitter Taste is combination of olfactory and gustatory sense anatomically just gustatory 0 Cells synapse with bers from cranial nerves Vll IX and X Know all of the cranial nerves and what they innervate for the nal 0 4 Pain touch and temperature 0 Poorly understood 0 Proprioception mediated by muscle spindles nerve endings wrap around specialized bers Muscle tension and position 0 5 Acousticolateralis Octavolateralis system 0 Senses of the lateral line and the inner ear 0 A key to the function neuromast Microscopic sensory organ sensitive to vibrations Handout 4 Waterborne vibration Cupula starts to vibrate gelatinous relative positions of the cilia moves and causes depolarization of the hair cell 0 Nerve bers innervate o Axons carry signal to CNS 0 A Lateral Line system synapomorphy of craniata develops from lateral line placodes ln shes and aquatic stages of amphibians Detects waterborne vibrations using neuralmasts Handout 4 0 Lateral line canals are located running rostrally to caudally on the head to the trunk canal like furrows every so often there s an opening lateral line pore o B Ampullary organs lnside there are series of neuralmasts Out would be water waterborne Vibrations come through the canal causing Cupula to vibrate signaling Fishes hear through lateral line not ear 0 Inner ear in tetrapods Specialized pitlike structures not canals Ex Ampullae of Lorenzini Synapomorphy of Chondrichthyes Detect electromagnetic elds 0 Modi ed lateral line canals Modi ed neuralmasts o C lnner ear The quotearquot has three components 0 Outer pinna external acoustic meatus Middle stapes malleus incus 0 Inner hearing balance and orientation 0 ln shes and aquatic amphibians the hearing part is lateral line detecting vibrations so inner ear only functions for orientation 0 ln tetrapods inner ear functions for all three Development 0 Inner ear from Otic placode by invagination o Membranous labyrinth Utricuus and sacculus two chambers Macuae s macula patches of neuromasts inside the chambers Spotpatch Semicircular ducts 3 each in different planes Handout 5 Labyrinth within the Otic capsule Perlymph uid around the membranous labyrinth Large chamber attached to endolymphatic duct 0 Extension of sacculus that s important for mammals Lagena has lagenar macula Semicircular ducts 2 vertical 1 horizotal 0 Blind ended ends are ampulla o In each ampulla neural masts known as Crista 1 at end of each duct Endolymph uid inside 0 Endolymphatic duct remnant of the stalk of invagination of the Otic placode 6 Photoreceptors o A Median eyes unpaired One or two found in most nonamniotes pineaand parietal eyes Not imageforming eyes Determine if light is present or absent above the head of the organism Parietal eye Handout 4 Overlying epidermis that has a clear area quotcorneaquot Socalled lens but not image forming o Directs light from above cornea onto the photoreceptive o Orientation and balance uid movement across the neuralmast coherent pattern of signally if spin around there isn t a pattern so get dizzy o Handout 6 Evolution of cochlea expansion and coiling of Lagena of Sacculus Lagenar macula modi ed into basilar papilla Cranial nerve 8 in mammals is vestibular cochlea nerve Two branches one innervates vestibule o Other innervates basilar papilla Facial nerve innervates behind the membranous labyrinth to innervate M stapedius layer parietal nerve innervates photoreceptor cells Can tell if another sh predator is swimming above you In birds and mammals pineal eye becomes the pineal gland an endocrine gland produces melatonin seasonal regulation of reproduction and daily regulation of the sleepcycle o B Lateral eyes paired Development Handout 8 A O O O Outgrowth of part of brain Diencephalon part of brain outgrowth known as Optic vesicle early in development of eye Optic vesicle induces overlying ectoderm to form lens placode Lens placode invaginates into optic vesicle Optic stalk precursor of CN 2 Optic Lens vesicle precursor of lens Causes a bilayer to form when invaginates Precursor of Retina o Pigment layer and neural layer Optic stalk modi ed to CN 2 CN 2 isn t even a nerve Actually a part of the brain braintrack technically not a nerve Structure Handout 7 Crosssection of lateral eye 0 Top is cornea down is retina optic nerve at bottom 0 Three layers 0 Outer brous layer sclera white of eye and cornea 0 Vascular tunic choroid Vascularizes the eye Gives rise to the iris Pigmented part of eye 0 Associated with contractile cells Pupil in center 0 Retina 0 Eye Ciliary body also associated with contractile cells Deform shape of eye to focus light onto retina Lens Contractile cells either constrictor dilute the pupil Optic disk where optic nerve attaches to retina Vitreous bodyhumor NERVOUS SYSTEM 0 1 Introduction 0 Functions to control and coordinate activities Endocrine also control system Nervous system works rapidly endocrine slower o A Structural organization The two basic structural components 0 Central nervous system CNS 0 Brain and spinal chord 0 Peripheral nervous system PNS o Cranial nerve and spinal nerves and ganglia 0 Some basic terms Nerve a bundle of nerve bers neuronal cell processes axons Neuron a nerve cell 0 Cells that are excitable capable of depolarization Ganglion a group of nerve cells bodies in the PNS o B Functional organization Somatic sense organ bers Visceral neurons of the gut and heart also neurons that innervate muscles of heart and gut Sensory afferent carry info to the CNS Motor efferent carry info awayfrom the CNS to periphery Handout 1 Neuron can be somaticvisceral sensorymotor Remove quotspecialquot category Visceral motor consists of only autonomic neurons 0 2 Components of the Nervous system 0 Neuron structure Cell body Dendrites small projections attached to cell body Axon long process running from cell body Neurilemma myelin sheath surrounding Telodendria o Handout 3 Cell body typically starshaped Small projections off are dendrites Axons form nerves End of axon are the Telodendria Axon surrounded by myelin sheath Neurilemma Neurons synapse with each other Synaptic cleft between Neurotransmitters released by Telodendria after depolarizes to cause the next neuron to depolarize Wave is known as action potential Neurilemma consists of myelin Small gaps in the sheath depolarization wave can hop over space to space so not propagated through entire axon o 8 hops o Increases the speed of transmission of the action potential 0 Receptors sensory structures Sensory nerves innervate sensory structures 0 Effectors structures that perform action Typically skeletal smooth or cardiac muscle Schwann cells cells that form the Neurilemma in the PNS o Neuroglia nonneuronal cells in the CNS Astrocytes Oligodendrocytes Microglia Handout 3 Astrocytes starshaped cells 0 Large 0 Stellate starshaped 0 Two functions provide nutrition for other cell types and physical support 0 A lot of processes coming off ectodermal Oligodendrocytes 0 Not many processes and smaller than Astrocytes 0 Form CNS Neurilemma o Ectodermal also 0 Microglia o Smallest of Neuroglia cells 0 Mesodermal o Critically they re phagocytic lngest bacteria or viruses that might be infecting the CNS Maintain integrity of CNS 0 Other important parts Ependyma epithelial lining of the central canal of spinal chord and ventricles of the brain 0 Meninges s meninx Outside of brain and spinal chord Protective and vascular layers surrounding the nervous tissue of the CNS 0 Meningitis is infection Central canal and ventricles lled with uid cerebrospinal uid 0 Those are the hollow part of spinal chord and brain Cerebrospinal uid 0 Fluid is what is taken in spinal tap


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