reproduction notes for chapters 4 and 6 for test
reproduction notes for chapters 4 and 6 for test AGSC 352
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This 8 page Bundle was uploaded by nicole l brown on Monday September 14, 2015. The Bundle belongs to AGSC 352 at Truman State University taught by Dr. Kelly Walter in Summer 2015. Since its upload, it has received 24 views. For similar materials see Reproduction Physiology in Agricultural & Resource Econ at Truman State University.
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Almost no time left on the clock and my grade on the line. Where else would I go? nicole has the best notes period!
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Date Created: 09/14/15
Repro Dr Walter Chapter 4 vocab Embryogenesis is the formation and growth of an embryo Formation of pituitary and reproductive tracts o This process involes the merging of different types of tissue 0 Careful timing required to avoid problems 0 There is No strict timeline because variances btw species 0 The Faults well result in repro failure of individual Organs differentiate from germ layers Differentiate differentiation the develop of the structure and function that is specialized more in the original cells or tissue Primary embryonic Germ layers the ectoderm mesoderm and endoderm These are the earliest recognizable forms of tissue structure in the early embryo o dermskinendo mesoectoinner middle outer 0 Endoderm is the closest to the middle of cells in the embryo 0 Gives rise to digestive tract pancreas lungs endocrine organs 0 Mesoderm middle layer of the embryo 0 Gives rise to circulatory skeletal muscular urinary system 0 Most of reproductive system 0 Ectoderm the outer layer in the embryo of the inner cell mass 0 Gives rise to central nervous system sensory organs mammary glands sweat glands skin hair claws hooves Embryonic development Zygote is the fertilized ovum 0 There are Two pronuclei 0 Haploid nucleus of a sperm or eggthat takes place before fusion of the nuclei in fertilization o Reorganization and or repair of nuclei 0 The Period of susceptibility to gene insertion Morula the multicellular step 0 This divides into blastomeres nondifferentiated initially 0 This is the stage scientists use for embryo splitting in controlled situations Blastocyst is a thin walled hollow structure 0 Blastocoele is a cavity in the embryonic develop 0 Trophoblast is the outer most layer of cells that well turn into placental tissue 0 Inner cell mass the lowermost layer is the endoderm the top layer uppermost is the epiblast 0 Early embryo l6days o Amnion the uid that has the nutrients o Yolk sack is surrounded by endoderm 0 Embryonic disk the dorsal view is ectoderm ventral view is endoderm o Primitive streak the migration of the mesodermal cells that go to the central region 0 Late embryo 21 days for human 0 Visible notochord the layers are the mesodermal tissue and the later forms of vertebrae 0 Somites develop the layers are skin connective tissue ectoderm 0 Fetusnewbom features embryo alien thing 0 Development of pituitary gland o Pituitary hormone is the hormone that stimulates follicle s also the hormones of luteinizing and prolactin o Pituitaryhypophysis there are 2 different sections 0 Anterior lobe of the pituitary adenohypophysis It is the glandular portion of the pituitary that is made from the stomodeal ectoderm tissue of mouth of the embryo This lobe produces gonadotropins FSH and LH adrencorticotropin ACTH thyroid stimulating hormone TSH growth hormone GH and prolactin stomodeumpart of oral cavity 0 Rathke s pouch diverticulum tissue well move from mouth and then cut itself off from the mouth 0 Posterior neurohypophysis this comes down from the bottom of the brain and it well meet the Rathke s pouch The tissue that moves down is called the infundibulum has axons and nerve terminals of neurons there cell bodies are located in hypothalamusdiencephalon oor of brain 0 Sphenoid bone sella turcica is a bone that grows around both lobes of the pituitary gland the bone cups the gland and there isn t a bone btw the brain and the gland 0 Sexual differentiation 0 Initial step when fertilization happens sperm well deliver either and X female Y male to the oocyte 0 Early embryo 15 gestation while yolk is present the primordial germ cells develop Is formed at the base of the hindgut then the Bipotential gonad it is capable of differentiating btw two develop Paths that can either develop into the testis or the ovary it is called the gonadal ridge on the dorsal body wall it is where the primordial germ cells go to To form the gonad of either sex Either the cells make it to the gonadal ridge or they degenerate This is the site of the mitosis happens and the number of cells increases quickly The act of the germ cells getting the gonadal ridge kicks starts the connective tissue of proliferates to form primitive sex cords these are the cord that well snake into the male gonad they turn into the seminiferous tubules Theses cords well push towards developing kidney Pronephros pronephric kidney it is the most primitive form of kidney that is found in the develop mammalian embryos that degenerates and gives way to the mesonephros The renal system develops alongside the repro system The 3 renal systems Pronephros is not functional piece of primitive kidney that is found in lower animals Mesonephros this well form urine that well be drained by bilateral pair of ducts that are called the mesonephric ducts they empty into the urogenital sinus Mesonephros mesonephric kidney is the last form of the kidney well appear at gestation This well develop Functional nephrons and well be the functional form of kidney in all adult mammals This 3035 gestation Paramesonephric ducts The mesonephros develops at the same time that the paramesonephric ducts develop Mesonephric ducts the ducts that well provide an escapes route for uid that is made by the mesonephros in the develop Embryo The paramesonephric forms on either side of the meson Duct and these well develop Into oviducts cervix and portions of cranial vagina At this time the embryo is still developing both sets of repro systems this stage is called the sexually indifferent stage Sexual differentiation This process for the male and it starts with the Y chromosome Sex determining region SRY this controls the pathway to the male develop develop Tests sertoli cells antimullerian hormones and more The process for the female and it starts with the X chromosome Most of the gonadal ridge becomes ovary Because of the lack of sertoli cells the anit mullerian hormone isn t secreted the Leydig cells then can t secrete testosterone so the male tract well dissolve The sex cords well break apart and forms cellular clusters and surround the primitive germ cells The clusters do snake into the interior of ovary but not as much as the male tract more ducts Follicles form on the outside of the ovary the female is born with the same number of gametes for the rest of that female s life these germ cells develop Fast in this stage Male process of development Mesonephric tubules these are the ones that well snake into the primitive gonad and make that connection with primitive sex cords rete tubules The meson Tubules well give rise to the efferent ducts The anitmullerian starts to repress the paramesonephric duct because the embryo is going to be male do the female repro tract isn t needed Testes grow and drop in to scrotum The process of the testis going in to scrotum the testes are now inside the hindgut of the animal and now since the male repro system has to be outside of the body the testes have to move in to the scrotum The gubernaculum is the tissue connective that is attached to the bottom of testis and the process second stage of growth of the gubernaculum growing pulls the testis to the outside of body The testes well get wrapped in the peritoneum Distal portion The testes have passed through the inguinal ring in to the scrotum The gubemaculum well start to regress and this is the last step to the testes going into the scrotum and the peritoneum 2 layers of peritoneum scrotum The layer that touches the testis is the visceral vaginal tunic then there is a space that is able to slide and move freely houses viscera The next layer is the parietal vaginal tun1c Hormones that contribute to the growth and movement of testes Testosterone is made in the Leydig cells in the testes Insulin like3 insl3 is synthesized and secreted by the islet cells in pancreas and also in Leydig cells This causes the growth and regression of the gubernaculum if the female is over exposed to this hormone results in abdominal descent of the ovaries The male problems Some of the problems that can come up are Cryptorchidism when the testes fail to move into scrotum Normally the testes descend around mid gestation in both the boar and humans and descend right before birth expect in stallions Common 35 Bilateral cryptorchidism is the form of this problem that results in the individual being sterile but they still have the ability to have testosterone and have normal sexual behavior Inguinal herniation the space btw the two vaginal tunics the space can get filled with portions of the intestines most common is swine Castration It is the removal of testes very common because of the benefits in livestock management Pros docile can mix with females no opps kids Cons can t breed an animal after castration so make sure you really don t want that animal as a breeding animal Female tract development Paramesonephric ducts includes the oviducts uterus cervix cranial vaginashould be review Mesonephric ducts not important in female the repro tracts are outside of peritoneum until the peritoneum surround the tract female has a double layer The broad ligament is formed from the gonadal ridge The ovaries and the rest of the tract stay in the same spot they settled in the gonadal ridge Problem s that can happen o Freemartin when twins of two different sexes develop In the cow They share a blood supply so the female is exposed to all of the male hormones so the tract won t develop Fully and the female well have act like a male testosterone females do have testosterone but not a huge amount Repro Dr Walter Chapter 6 vocab 0 Male vs female 0 Male hypothalamus 0 It is Established prenatally 0 Testosterone defeminizes brain 0 Defeminizing is when testosterone is converted to estradiol By the testosterone crosses through the bloodbrain barrier and it is then converted into estradiol and it gets ride of the surge center of the brain 0 Female hypothalamus 0 Lacks testosterone and has the GnRH surge center in the hypothalamus 0 The hypothalamus has a surge center that is protected by the alphafetoprotein this binds to the estradiol and won t let it pass through that barrier into the brain 0 Endocrine profiles 0 Male GnRH does not work in the male because of the lack of the surge center There is a constant secretion in a pulsating pattern about every 26 hrs This gland release LH in a steady pulse This also secretes testosterone in a pulse to 0 Female the surge center releases estradiol and LH every 20 days 0 Puberty 0 Is the ability to reproduce successfully this is true for both the male and female This happens over time and how this process gets started is by the secretion of GnRH at the appropriate frequency and quantities to stimulate the gonadotropin these are release by pituitary The gonadotropins help to promote the steroidogenesis gametogenesis and the development of reproductive tissues 0 Female 0 Age at first estrus or heat this is the stage when the female shows behavioral signs showing that she is receptive to a male 0 Age at first ovulation this can be determined by a manual or visual validation but this has to be done 9can be difficult in laparoscopy or endoscopy first time heifers ovulate it is not followed by behavioral estrus is it called silent ovulation the age of first estrus and ovulation can differ 0 Age at which pregnancy can be supported without deleterious effects this is more from a practical point of view 0 Males Age when behavioral traits are expressed this can be seen by mounting and showing an erection They will try these behaviors even if there aren t fertile Age at first ejaculation this is when the ejaculation process is functional This process has to have coordination of the nerves glans and muscles This process can be premature they aren t fertile yet Age when spermatozoa first appear in ejaculate this is when the body can produce seminal uid and be able to ejaculate but this is still before spermatozoa are fertile In a management standpoint you can determine this by collection every week Age when ejaculate contains threshold of spermatozoa the number of sperm can be to lower to even fertilize anything know your minimum Before puberty the distribution and morphology of neurons secrete GnRH increase in neurons as puberty begins The function of GnRH that secreting neurons are in uenced by the plane of nutrition this is where females have to acquire a certain body size degree of fatness Exposure to environmental and social sues this can determine on season and photoperiod also the presence of the opposite sex and the density of group housing can be a factor Genetics this can vary on breed variation Female fatness The focus is on energy maintenance of the vital physiologic functions the least important are the nonessential process of repro Increase of growth and energy intake the bodies mass well increase but the surface area of the body decreases this can shift the metabolic expenditure and it allows non vital physiologic functions to start developing There is no certain threshold level for fat build up that can be determined high frequency GnRH pulses are in uenced by glucose and the free fatty acid concentrations that are present in blood Leptin It is a hormonal peptide bond that is secreted by fat cells This is increased in blood and that increases adipocytes fat cells The receptors are present in the anterior lobe of the pituitary and hypothalamus This plays an important role in controlling the onset of puberty and it can signal to hypothalamic neurons when a certain degree of fatness has been achieved Environmental and social conditions The external factors have a big in uence on when puberty happens The sensory neurons of the optic and olfactory systems are anticipated by the environmental information This process is stimuli by CNS and delivered as neural inputs to the GnRH neurons of hypothalamus high frequency and low amplitude pulses of GnRH at an earlier age is the hypothalamus The month that the animal is born can in uences age of pubertyreally in seasonal breeds for example sheep begin estrous cycles because of the short day lengthslamb born in spring reach puberty at 56 months of age fall lambs reach pub At 1012 monthsheifers born in fall go into earlier puberty than those born in springthe exposure to the long photoperiods at those 6 months of their life makes puberty happen faster Social cues it is caused by the olfactory recognition of the phenomenal substances in the urine When females are in the presence of male this can get puberty on faster these females have a greater chance of becoming pregnant the size of the group can make pub Happen faster bigger group better
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