chapters 8 and the beginning of chapters 9
chapters 8 and the beginning of chapters 9 AGSC 352
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This 4 page Class Notes was uploaded by nicole l brown on Saturday October 3, 2015. The Class Notes belongs to AGSC 352 at Truman State University taught by Dr. Kelly Walter in Summer 2015. Since its upload, it has received 11 views. For similar materials see Reproduction Physiology in Agricultural & Resource Econ at Truman State University.
Reviews for chapters 8 and the beginning of chapters 9
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Date Created: 10/03/15
Repro Dr Walter Chapter 8 slide 23finish 2cell 2Gonadotropin model LH binds to its specific membrane receptors on the theca interna This converts cholesterol to testosterone and then testosterone moves to the granulosa cells Those cells contain FSH receptors and that binds to its receptors and causes the testosterone to be made into estradiol This model only functions until estrogen gets to the threshold that can causes preovulatory LH surge The synthesis of LH receptors by the granulosal cells is important step in preparation for ovulation LH receptors allows LH surge to exert full effect on follicle to cause ovulation Its primary target for estradiol is the repro tract tissue mucosal epithelium responds dramatically cervix and cranial vaginal is where the mucus is produced uterus is where the develop Of uterine glands cilia of oviduct increase beat frequency the blood flow increases to all repro organs and that causes the swelling of the vulva see this during estrus facilitates secretions and allows delivery of leukocytes Preovulation is when the LH surges start the series of events that is necessary for ovulation The ovulation is then destruction for follicular tissue Then the prostaglandins PGEZ and PGF 2 alpha are important Blood flow to the ovary is 7 times higher around the time of LH surge Hyperemic is the local elevated blood flow this is controlled by histamine and PGE2 the histamine also can causes edema in the theca interna and this increases vascular permeability o Theca interna the shifts from testosterone to progesterone production o It has local production of progesterone that is needed for ovulation to occur stimulates collagenase synthesis by the theca interna this then causes break down of collagen and the connective tissuecomponent of tunica albuginea 0 While this is going on the follicular fluid increases this created apex of follicle stigma and this pushes outward and further weakens wall Dominant follicle then produces angiogenic factors this is the substances that promote growth of the new blood vessels The net effect of the increased blood supply and the flow of the dominant preovulation of the follicle that is provided with hormonal and metabolic steps for final maturation Uterus secretes and synthesizes prostaglandins and that causes 0 PGR 2 alpha this causes lysosomes in granulosa cells to burst and that release of enzymes that further deteriorate connective tissue And this also causes contractions of hyoid components of the ovary and that increase pressure locally protrudes stigma more 0 PGEZ helps the follicle remodel to CL after ovulation and the it activates plasminogen to become plasmin which actives enzymes for tissue remodeling Spontaneous vs reflex In spontaneous ovulators o Ovulations occurs regularly It is the response of hormonal changes It does not require copulation o For ex cow sow ewe mare woman Reflex induced ovulators o This requires stimulation for vagina and the cervix 0 Has longer copulation duration increased frequency of copulation this makes sure that the animal has adequate neural stimulation to cause ovulation o EX cats rabbits ferrets minks o This can be induces by artificially electrically or mechanically o Tactile stimulation can help with copulation by being converted to action potentials travel to spinal cord afferent pathways innervate hypothalamus it increases firing of the neurons and that can result in GnRH surge 0 Cats single copulation induces ovulation 50 of the time o Rabbits time of ovulation can be controlled 0 Camelids camels llamas alpacas modified induced ovulators this is when seminal plasma induces ovulation GnRHlike when is injected into rabbits and this causes LH surge They copulation for a long time about 1 hour Artificially induced Folliculogenesis and ovulation You have to understand the process and what hormones require for follicular dynamics and ovulations to be about to manipulate it There are two approaches 0 you can hormonally induce ovulation 0 this requires premature luteolysis it is made by exogenous PGF 2 alpha this lyses luteal tissue and then drops progesteronethen endogenous GnRH is released and then the LH FSH is released form AP 0 you can superovulation 0 they have a high number of follicles selected they have a greater number of ovulations it is made by injections of eCG FSH and LH GnRH this provides greater follicular development dosages and types vary oocyte maturation This is not limited to just the follicular phase it happens throughout life 4 phases 0 Mitotic division of the primordial germ cells prenatally this ensures female born with supply of germ cells follicular reservoir stops after birth This is when the primary oocyte enters the first meiotic prophase 0 Nuclear arrest nucleus becomes dormant and remains until post puberty nuclear arrest inhibits DNA so it is not vulnerable to insult cell death 0 Cytoplasmic growth accumulation of the cytoplasm and the development of the zona pellucida Junctional complexes permit ionic and or electronic coupling btw the different cell types this is called gap junctions and it can provide contact with granulosal cells s cytoplasm can develop o Resumption of meiosis Chapter 9 luteal phase 0 Luteal phase goes one from time of ovulation until Luteolysis of CL this includes Metestrus and Diestrus The hormone that helps this process is progesterone luteolysis is because of prostaglandin F2 alpha 0 Luteinization Synthesis and secretion Luteolysis 0 Dominant follicle to ovulation o The follicle ruptures at ovulations and that causes blood vessels within the follicle wall to then rupture The results are bloodclot appearance this is called corpus hemorrhagicum it is seen from the time of ovulation until 13 days of estrous cycle lose hemorrhagic appearance and starts Luteinization which increase in size starting day 35 0 CL to CA 0 The CL well increase in size and mass until the middle of the cycle this is its function 0 Luteolysis happens near the end of Diestrus this loses functional integrity and decreases size Luteolysis is when there is irreversible structural damage to CL the regressed CL that becomes corpus albicans or white body CA is seen throughout several estrous cycles White scarlike the appearance because of the connective tissue that remains and glandular tissue disappeared o Luteinization o The theca interna and granulosa cells turn into a functional luteal tissue LH helps in this process 0 Before ovulation the some of the basement membrane disintegrates The thecal separates and the granulosal cells disappear 0 During ovulation the follicular fluid can leak out the wall of the follicle collapses this then can form a lot of folds 0 After ovulation the folds begin to become interdigitate the glands are formed of connective tissue cells and thecal cells and granulosal cells 0 Thecal and granulosal cells mix the exception is in women and primates the clumps of thecal and granulosa cells are called islets o The difference btw luteal cells of the granulosal or thecal origin the large luteal cells LLC are made from granulosal cells the small luteal cells SLC are made from the thecal cells and the connective tissue is from the remaining basement membrane portions 0 Luteal cells 0 LLC of the granulosal origin the size can vary btw species about 2070 micrometers Ruminants LLC contain dense secretory granules close to the plasma membrane the secretory granules contain oxytocin in the CL of regular cycle and relaxin in CL of pregnancy 0 SLC is from the thecal cells it is less than 20 micrometers in diameter it is irregularly shaped more than one lipid droplets in their cytoplasm it does not contain secretory granules in LLC o LLC and SLC are steroidogenic it has the ability to make steroids 0 CL The CL increases in size until midway through luteal phase It determines the presence and absence of the CL by using rectal palpation in cows also it cannot predict functional status of CL accurately mares CL doesn t protrude from ovary surface The class if compared with the actual blood concentrations of progesterone 0 2539 cows are classified as having a functional CL but they were not at high progesterone levels 0 1521 cows are classified as having a nonfunctional CL with high progesterone o Rectal palpation is not useful in IDing the presence of CL but has limits in predicting functional status Ultrasonography effective for CL examination in cows progesterone the concentration in blood is related to the diameter of CL 0 Luteal cells 0 LLC never really multiply after ovulation the LLC in CL number is determined by the total number of granulosal cells that are given by follicle The function can be related to the number of granulosa cells of the follicle prior to ovulation 0 CL increases in size and weight happens because of 3 times increase in vol of LLC and 5 times increases in number of SLC So as the CL grows the LLC goes through hypertrophy and SLC goes through hyperplasia