Lecture 9 orgogenesis and histogenesis
Lecture 9 orgogenesis and histogenesis Zol 328
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This 6 page Class Notes was uploaded by Kelsey Bowe on Tuesday March 29, 2016. The Class Notes belongs to Zol 328 at Michigan State University taught by Dr. Pam Rasmussen in Spring 2016. Since its upload, it has received 43 views. For similar materials see Comparative Anatomy and Biology of the Vertebrates in Biology at Michigan State University.
Reviews for Lecture 9 orgogenesis and histogenesis
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Date Created: 03/29/16
Notes Lecture 9 orgogenesis and histogenesis (ch 5) v End Nuerulation/ beginning orgogenesis - animal/vegetal poles replaced by bilateral symmmetry and anterior/posterior axes - 3 main germ layes are now distinct orgogenesis formation of organs from tissues -may include tissues from a combination of two germ layers histogenesis formation of tissues from germ layers -tissue aggregation of similar cells perfoming the same function -four major types of tissue: epithelium, connective, muscle, nervous • Germ Layer Derivatives [textbook figure 5.17] prof never specified how much we need to memorize -Ectoderm gives rise to: epidermis stomodeum (anterior mouth) proctodeum (cloaca) extraembryonic membranes brain and spinal cord peripheral nervouse system ectomesenchyme visceral skeleton cranial muscles teeth -Mesoderm gives rise to: somites (dermis, musculature, vertebral column ) nephrotome (kidney and urogenital tracts) somatic hypomere ( appendages, paritoneum, gonads) splanchnic hypomere ( heart, vessels, mesentaries) -Endoderm pharnyx and posterior mouth posterior foregut (esophagus and tracheal tube) midgut (stomach, liver, pancreas, intestines) hindgut (bladder, cloaca) v Epithelium closely adjoined cells, little extracellul ar matrix between -one side of the epithelium rests upon a basal layer/basement membrane which is composed of two structures: basal lamina: derived from epithelium and the reticular lamina: derived from connective tissue -this basement membrane of 2 layers acts as a selective barrier to the epithelium cells -free/apical surface opposite side of epithelium layer, opens to the exteriror environment or a cavity/lumen -at the free surface of epithelium excretory products can be released and other materials may be taken up by the cells Two main types of epithelium: -membrane epithelium cover the surface of or line body cavities , ducts, and lumina (cavity) of vessels endothelium lines blood & lymph vessels mesothelium lines body cavities Types of epithelial membrane cells: • simple single layer of cells • statified multiple cell layers • squamous flat cell • cuboidal cube shaped cell • columnar tall cube shaped cell • pseudostratified staggered arangement of nuclei in tall cells -found in transistional epithelium which lines bladder & urinary ducts -glandular epithelium/glands specialized cells that secrete a product, two types: -exocrine gland glands with a duct to collect product and carry it away can be tubular/cylindrical or alveolar/acinar/rounded duct can be simple (only one) or compound (multiple ducts) -endocrine gland glands where the product is taken away by circulatory system organized into cords/sheets and clumps/solid mass or into follicles (tiny hollow sphere) • Connective Tissue “misfits of histology” -includes bone, cartilage, blood, adipose (fat) tissue, and fibrous connective tissue -fibrous connective tissue forms tendons, ligaments, parts of dermis, outer capsules of organs consists of fibroblast cells and an extracellular matrix of protein fibers originates from mesenchyme (which is an embryonic tissue, but not a major germ layer) -hemopoietic/blood tissue form blood cells, two types: myeloid tissue found in bone cavities lymphoid tissue founf in spleen and lymph nodes -mineralization process of inorganic ions becoming depositied in the matrix of tissues, occurs in dentine, enamal, bone, and cartilage • calcification calcium carbonate or calcium phosphate is deposited into matrix • ossification (unique to vertebrates) bone formation by deposistion of calcium phosphate/ hyroxyapatite -cartilage firm and flexible connective tissue, consists of a ground substance made of chondroitin sulfate and fibers made of collagenous protein or elastic pr otein. avascular lacunae space within cartilage matrix where the cartilage cells/chondrocytes are found types of cartilage: -hyaline cartilage widespread, makes up bones before ossification takes place, remains in adults at tips of long bones, tips of ribs, tracheal rings, parts of the skull. Contains a homogenous mixture of collagen protein fibers -fibrocartilage contains a lot of collagen fibers, aids in resisting compressive force. Found in intervertebral disks, pubic symphysis, and within the knee -elastic cartilage flexible and springy, containes elastic fibers rather than collagen. Found in the ear and epiglottis -bone specialized connective tissue where organic salts are deposited (calcium phosphate and others), usually vascular, may be cellular or acellular osteocytes cells that make up fully formed bone osteoblasts produce new bone (osteogenesis) osteoclasts remove bone types/classifications of bone: -cancellous/spongy bone porous -compact bone more dense -cortical bone outer cortex -medullary bone core -nonlamellar disorderly arrangemt of collagen -lamellar orderly arrangement of collagen -Haversian bone special type of lamellar, where organic salts are in higly ordered units/osteons ostean/unit ring of bone around a canal where vessels and nerves travel -zonal bone exhibit periods of sustained mineral deposition interrupted by lines of arrested growth -endochondral bone cartilage or replacement bone, forms of cartilage from the mesenchyme and becomes replaced by bone, may contain 3 regions -Intramembraneous bone bone forms directly from mesenchyme • dermal bone from directly through ossification of mesenchyme, found in d ermis • sesamoid bone form directly within tendons • perichondral/periosteal bone form from deep cell layer of fibrous connective tissue that covers bone or cartilage, appositional growth • secondary cartilage forms after a bone breaks (birds and mammals only) taxa and their bone types -gnathostomes: all have osteons -fish: may have acelluar and cellular bone -amphibians&reptiles: typically cellular and lamellar, new bone formed on a seasonal basis -non primate mammals: may have few or no osteons, acellur and non vascular bone present in some areas -primates: extensive system of osteons *fish, amphibans and reptiles continue to grow bones throughout their life, birds and mammals do not bone repair -new bone replaces old bone on a regular basis, osteoclasts erode old bone and create empty channels, and osteoblasts quickly refill -if a bone break severly, the process is more complicated: 1 blood clot forms 2 callus forms from activity or periosteal cells 3 endochondral bone replaces callus, cartilage calci fies 4 osteoblasts and osteoclasts remodel the mend, bone matrix appears again joints -joint/articulation where separate bones/cartilage make contact -synovial joint/diarthrosis joint that permits movement -synarthrosis restrictive or no movement at all, several types: • synostosis connection between elements is made of bone • synchondrosis if connection is of cartilage • syndesmosis if connection is of fibrous connective tissue • Neural Crest and Ectodermal Placodes similar cells development, different functions and differentiation -neural crest cells (ectoderm derivative) set aside early in development, then migrate and differentiate into many structures. break loose from surface epithelium, clump together above the developing neural tube migrate into embro to permanent sites for developing into final structures may become: ganglia of nerve cells, insulating sheath of peripheral nerves, pigment cells, hormone producing cells, parts of skull and lower jaw, odontoblasts (dentin secreting cells in teeth), connective tissues, heart muscle -ectodermal placode cells formation varies by taxa: teleosts: form as solid buds, secondarily form a cavity other vertebrates: thick areas of surface ectoderm tht sink inwards, form specific sensory receptors types of placode: • dorsolateral placode contribute to lateral line receptors, vestibular apparatus (balance sensing) of otic (ear) capsule, and ganglia of cranial nerves • epibranchial placode ganglia of cranial nerves • olfactory placode form at tip of head, become sense of smel (type of sensory nerve), grow and connect to brain • optic placode paired, produce lens of eyes • adenohypophyseal placode unpaired, contributes to pituitary * fish and amphibians: the dorsolateral and epibranchial placodes lie in two rows just above gill slits v Extraembryonic Membranes (Amniotes only!) intrinsic membranes that arise from germ layers and suuround developing embryo. Secrete wastes, nutrient transport, gas exchange, contain the embryo in a fluid filled capsule. -types of extraembryonic membrane yolk sac formed from bilaminar splanchnopleure (endoderm) and the splanchnic (mesoderm) amniotic folds two membranes that cover the embryo, formed of somatopleure (ectoderm) and somatic mesoderm: amnion immediatly surrounds embryo chorion outer membrane Allantois eventualy fuses with chorion, arises from hindgu t (ectoderm) Respirtory membrane arises from chorion and allantois Placenta formed by parts of extraembryonic membranes, may also comprise from cells of mother (can be found in vivaparo us fish, reptiles and ampibians) placentome placenta like structure found in some reptile, formed of uterus and chorioallantoic membrane v coelom the main body cavity in vertebrates, divided into two main cavities: -pericardial cavity contains the heart -pleuroperitoneal cavity contains most other organs -transverse septum fibrous partion that separates the two main body cavities -variations of body cavities -pleural cavity found in crocs, turtles, birds, some lizards; separate compartment that holds the lungs, separated by the pulmonary fold *pleural cavity also found in mammals but differs developmentally, each lung in a mammal is confined to its own cavity, with the cavity wall called the coelomic fold *coelomatic fold becomes the diaphragm , important musculature to help inflate the lungs v maturation -metamorphosis radical postembryonic change in body structure of a juvenile to its final adult form -heterochrony difference in the timing of appearance of a trait between a species and the ancestral condition • paedomorphosis juvenile characteristics remain in adults • progenesis: early offset • neoteny: slow rate • postdisplacement: late onset • peramorphosis exaggeration of an ancestral character • hypermorphosis: late offset • acceleration: fast rate • predisplacement: early onset v Biogenic laws -Haeckel: individual pases in development through breif stages (recapitulation ) -Von Baer: development proceeds from general to specific Pleiotropy single gene has multiple effects on unrelated traits v epigenomics/epigenetics study of variation in individuals caused by switching genes on/off due to external environmental factors
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