rest of chapter 9 and chapter 10
rest of chapter 9 and chapter 10 AGSC 352
Popular in Reproduction Physiology
Popular in Agricultural & Resource Econ
This 9 page Class Notes was uploaded by nicole l brown on Saturday October 10, 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 12 views. For similar materials see Reproduction Physiology in Agricultural & Resource Econ at Truman State University.
Reviews for rest of chapter 9 and chapter 10
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 10/10/15
Repro Dr Walter Chapter 9 slide 20 the end of the chapter Functional capability of CL Secrete progesterone The functional ability is depends on the number of luteal cells and vascularity in the cell layers of the follicle also this is in charge of the synthesize and deliver hormones the follicular uid contains angiogenic factor the degree that the vascularization alters functional capability for the later forming CL When the luteal is not functioning well enough that is because of bad progesterone synthesis and secretion and this is thought to be a factor in repro failure Target organs for progesterone The target is progesterone and this is goes to the hypothalamus uterus mammary gland 2 target components for the uterus glandular epithelium this stimulates the max secretion by the endometrial glands and this supports the development of free oating conceptus after it goes into the uterine lumen Muscular myometrium this inhibits contractions of the uterus uterine quiesecence But in mares the conceptus is moved around the uterus This causes the final maturation of the mammary gland This inhibits GnRH release Progesterone inhibits Estrual behavior The hypothalamus has negative feedback from progesterone this reduces the pulse frequency of the GnRH by the tonic center high amplitude of LH FSH secretion only allows some follicles to develop in the luteal phase they don t secrete steroids This inhibits Estrual behavior and that causes positive priming effect on the brain that enhances the effects of estradiol Luteolysis CL losses progesterone secretion After that is the loss of luteal tissue mass this happens over 13 days at the end of the luteal phase It cant be revered and the signfinagent from in progesterone concentration in blood PGF 2alpha comes from the uterine endometrium the luteolysis fales when the uterus and CL have a communication gap then the animal can be in a sustained luteal phase Transport of PGF2alpha to ovary This is responsible for luteolysis and uterus has to be near ovary PGF2alpha is moved by using the vascular counternurrent exchange This happens because two blodd vessels are close in promixity and run in different directions by diffusion the molecules move from a high concentration to a low concentration This allows high conentrations of PGF2alpha right to the oary it is not diluted in the systemic circulation important because of the ablity for PGF2alpha to denature fast mare doesn t show the countercurrent heat exchange mare s CL is sensitive to PGF2alpha so it does not metabolize quickly Secretion of PGF2alpha Ruminants have LLC that synthesize and or secrete oxytocin in the granules PGF2alpha well follow oxytocin in the blood PGF2alpha exact stimulus is controversial progesterone has to be elevated for several days and the uterus has to be exposed to it There is a change in pulsatile of PGF2alpha before luteolysis The exact interactions of progesterone concentration is oxytocin and PGF2alpha secretion not really know why Mechanisms responsible for luteolysis Just theories PGF2alpha causes the reduction of blood ow to the CL by vasoconstriction The capillaries degenerate and PGF2alpha bind to the receptors for LLC and that tiggers the event leading up to the death of the LLC and this stops steroidogenesis Cytokines is released from the immune system or lymphocytes this can cause luteal cell death and this can inhibit progesterone synthesis Luteolysis different in womenprimates Ovarian cyclicity does not need uterectomy this is thought to be related to oxytocin release from the posterior pituitary this causes the release of PGF2alpha in small amounts inside the ovary local only and only in small amounts of PGF2alpha Uterus synthesizes PGF2alpha that is needed to initiate menstruation this hormone is from the endometrium that then causes local vasoconstriction and this leads to necrosis and the sloughing of endometrial tissue Using knowledge of hormones to manipulate estrous cycle Hypothalamus has a negative feedback on it because of progesterone this feedback suppresses GnRH it suppresses GnRH and we can get artificial CL by the administration of exogenous progesterone this suppresses estrus and ovulation proestrus and estrus in the next 23 days has the removal of exogenous progesterone this alloes synchronization of multiple females this increases ease of management when using AI but in women this is intended to block ovulation and minimize the probability of pregnancy The primary method of estrus synchronization in mares is the progesterone supplementation common name is Regumate it is synthetic progesterone that is called altrenogest but it acts in the physiologic way as progesterone This is used in mares because it induces regular cyclicity from winter anestrus to the breeding season this also suppress undesired estrous behavior and it allows for breeding to be scheduled during the breeding season This is given by syringedosing orally or it can also be top dressing in feed It is given every day for 15 days this suppresses GnRH and keep in mind that when you stop this drug estrus well happen in about 45 days Exogenous PGF2alpha is potent luteolysin and it can also synchronize estrous the common name is lutalyse it is an injection that is given btw day 718 causes cattle to begin estrus in the next 3 days btw l6 days the drug has no effect because of the none functional luteal tissue When you combine progesterone and PGF2alpha is great to use synchronize estrous CIDR is the controlled internal drug release the dive to synch estrus is the intravaginal progesteronereleasing device it can be used to advance the first estrus in postpartum cows and prepubertal heifers and this is given by placing it in the vagina and left there for 7 days after insertion the progesterone concentration in the blood increases On the 6th day of CIDR you inject PGF2alpha once you remove the CLDR the day right after the decline of progesterone is followed by elevated GnRH this has elevated gonadotropins and follicular develop Inside 23 days then proestrus and estrus is within 23 days Another way is to use GnRH and PGF2alpha is developed by the reproductive physiologists at the university of Wisconsin and Michigan state This is called Ovsynch you don t have check for visual clues of estrus timed arti cial insemination is used mostly used in the dairy industry This has mechanisms of follicular dynamics and luteolysis 0 Steps for ovsynch GnRH is injected in cows that are ready for insemination if follicle is less than 10mm then giving GnRH causes ovulation and the CL to form it there isn t a dominant follicle present then giving GnRH will promote follicle growth Inject PGF2alpha in 7 days after GnRH this causes luteolysis in cows they enter follicular phase The second injection of GnRH 48 hours after step 2this causes ovulation of the ne developed follicle 16 hours after step 3 the cow needs to be inseminated you can t see estrus and you don t need to 0 Dairy herds that use this they get a better conception rate without having to look for detection The first injection of GnRH is given at random and the recommendation is 60 days waiting period after having a calf But there can be some problems if cow isn t cyclic then GnRH wont start the cyclicity PGF2alpha is not effective because of the lack of CL 0 Different issues we use presynch program is used this starts 26 days before the rst GnRH injection The cows are given PGF2alpha at random if it is after day 6 then the CL well regress The second PGF2alpha is given 14 days later 12 days later you have to give the first GNRH injection Recap Luteal phase is made up of 3 major processes Luteinization synthesis and secretion of hormones luteolysis The regressionof CL by PGF2alpha it is synthesized and secreted by the uterine endometrium in most species Hypothalamus has negative feedback from progesterone this inhibits GnRH secretion but the removal of progesterone equals the enter new follicular phase Progesterone PGF2alpha GnRH can be used to manipulate and or synchronize estrous cycles in most species Repro Dr Walter Chapter 10 Endocrine release in male Before spermatozoa can be made there needs to be an adequate secretion of GnRH from the hypothalamus FSH and LH secretion is from AP the secretion of gonadal steroids or testosterone and estradiol Hypothalamus doesn t have a surge center GnRH discharge in the frequent intermittent stages throughout the day and night they are only short bursts that only last a couple of minutes this can cause discharge of the LH that follows almost right after LH discharge lasts about 1020 minutes and it occurs 48 times over a 24 hour period FSH discharge concentration is lower but it has a longer duration than LH this is caused by the constant secretion of inhibin by the sertoli cells and a longer halflife of FSH In the testes LH well act on the Leydig cells this is comparable to the theca interna cell of the follicle in the ovary of the female It has membrane bound receptors for LH after LH binds to receptors the Leydig cell synthesized testosterone The pulsatile of the LH discharge is vital for testicular function Leydig cells can be unresponsive and there can be decreased LH receptors if there is a prolonged concentration of LH The timed discharge gets the optimal LH receptor number and testosterone secretion by the Leydig cells Testosterone concentration The intratesticular concentration of testosterone is 10500 times higher than systemic circulation The high concentration is needed for normal spermatogenesis Testosterone enters systemic blood circulation that is diluted over 500 times more this keeps systemic concentrations below the level this would cause negative feedback and the downregulation of the GnRHLH pulsatile secretions when it is resealed The pulsatile secretion of testosterone is needed for testosterone to have a negative feedback on GnRH and LH and FSH FSH is needed for Sertoli cell function because of this constant drip of testosterone this causes decreased FSH and it would decrease sertoli cell function and there would be a decrease in spermatogenesis LH is needed for testosterone production the constant supply of it will decrease LH and decrease testosterone produced So more testosterone all the time is having a negative feedback on itself Estradiol is also present in males Sertoli cells turn testosterone to estradiol This is comparable to the granulosal cells in the follicle in the female The 2cell 2 gonadotropin model this contributes to the negative feedback on the hypothalamus the high concentrations of estradiol then results in the suppression of GnRH and that leads to LH and FSH release to decrease Sertoli cell secretions it secretes inhibin which suppresses FSH secretion from anterior lobe of pituitary activin starts FSH secretions from anterior lobe of pituitary and dihydrotestosterone classification is an androgen hormone that is made by converting testosterone it helps With development of male sex characteristics Spermatogenesis This is the process of making spermatozoa it is made in the seminiferous tubules and it is made up of cell divisions and morphologic changes that can happen to the developing germ cells It has three phases proliferation meiosis differentiation Sequence of spermatogenesis The proliferation phase this is made up of mitotic divisions of the spermatogonia The generations of Aspermatogonia divide to generate large number of Bspermatogonia The meiotic phase begins With the primary spermatocytes It makes the genetic diversity this stops With the second meiotic division and this makes haploid spermatids The differentiation phase is When there aren t any more cell divisions in this phase Common name is Spermiogenesis its shape is spherical and it is undifferentiated spermatid that is transforms into the fully differentiated high specialized spermatozoon It is made out of a head nuclear material agellum tail Spermatogenesis It is the most immature germ cell or spermatogonia that is found at the periphery of the seminiferous tubule that is near the basement membrane As cell goes through the proliferate it gets closer to the lumen that is in the seminiferous tubule The developing germ cells are linked to the intercellular bridges This is made up of cytoplasm of all the cells of the same type in that group The number of cells that is interconnected is not known but they think that there are about 50 This provides communication btW cells to help With the synchronized development of the germ cells Proliferation This makes spermatogonia that is designated to become more advances cell type Spermatogonia are the most primitive type of cells that run into the seminiferous tubules It is diploid cell and it found in the basal compartment of the seminiferous epithelium it undergoes several mitotic divisions Three types of spermatogonia Aspermatogonia this undergoes a couple of mitotic divisions to progress from A1 to A4 Ispermatogonia or the intermediate B spermatogonia a mitotic division that is from primary spermatocytes A buildup of stem cells that is maintained so that the process can continue indefinitely the stem cells divide mitotically to allow a continual source of Aspermatogonia so that the spermatogenesis is able to keep going uninterrupted for years Meiotic phase It is responsible for the reduction t haploid state The primary spermatocyte is made by the mitotic division of Bspermatogonia this enters the first meiotic prophase The meiotic division first creates secondary spermatocyte and the secondary spermatocyte then quickly undergoes the second meiotic division spermatids is haploid spherical cells Differentiation phase The differentiation allows for the spherical spermatids to convert to a series of changes that allow for the spermatozoon to come get the ability to deliver male genetic material to an oocyte and to achieve fertilization This is made up of the Golgi phase cap phase acrosomal phase and maturation phase During the differentiation the nucleus then becomes condensed and the acrosome forms The cells can become motile by the developing agellum and the mitochondrial helix Differentiation phase Golgi phase This is characterized by the first steps in the develop of acrosome the acrosome is the membranebound organelle of the spermatozoon that covers the anterior third up to half of nucleus it also consists of the proteolytic enzymes that have to have penetration of the zona pellucida The new developed spermatid is made up of a large highly developed Golgi apparatus that is found by the nucleus This has small vesicles the intracellular packaging system is in all of the secretory cells The next step is the acrosome The proacrosomic vesicles from fuse and generate large vesicle that is called acrosomic vesicle It is made up of the dense acrosomic granule It has a smaller Golgi vesicle that is continually added to increase the size of acrosomic vesicle During the acrosomic vesicle formation the centrioles migrate from the cytoplasm to the base of the nucleus The proximal centriole develops into the implantation apparatus that connects the agellum to the nucleus The distal centriole develops into the axoneme of the central portion of a agellum tail of sperm Differentiation phase cap phase The acrosome forms a distinct and noticeable cap over the anterior portion of the nucleus The Golgi has to perform its function by packaging acrosomal contents and the membranes This moves from the nucleus to the caudal end of the spermatid It eventually disappears and the primitive agellum or tail is made from the distal centriole starts to project to the lumen of the seminiferous tubule Differentiation phase acrosomal phase The acrosomes well continue to spread until it covers two thirds of the anterior nucleus Nucleus starts to elongate Manchette is the system of microtubules that is made near the area of the posterior nucleus Parts of it attach to area posterior to the acrosome and some of the microtubules become the postnuclear cap Differentiation phase maturation phase The Manchette microtubules direct the formation of the postnuclear cap Mitochondria move to the bundle of agellum They orient around the agellum in a spiral fashion It makes the middle piece of the differentiated spermatozoa Flagellum has these dense outer fibers that make the final assemblies complete The whole spermatozoon is covered with plasma membrane Release of spermatozoa The sertoli cells release spermatozoa into the lumen of the seminiferous tubule This is called the spermiation it is the same as the ovulation in the female with the exception of spermiation that happens steady throughout the testis Head of spermatozoon Different shape for each species in mammals it is oval or attened Chromatin has a high degree of crosslinking and it is compacted The DNA within the sperm head is inert until fertilization or crosslinking reduced This is a mechanism that is thought to prevent the damage to the DNA btw spermiation and fertilization The acrosome covers the nucleus of the anterior about two thirds the ways It is made up of hydrolytic enzymes the acrosin hyaluronidase zonalysin esterases acid hydrolases But this is needed for the penetration of the zona pellucida of ovulated oocyte Acrosome reaction during the fertilization acrosome undergoes this process it is specialized exocytosis and the release of the enzymes then goes to digest and or penetrate zona pellucida Head of spermatozoon It is made up of capitulum middle piece principle piece terminal piece Capitulum it fits into the implantation socket of the posterior nucleus it connects the tail to head This is made up of the laminated column gives exibility and or motility this allows for the movement from side to side of the agellar beat Axonemal component of tail is the way it is placed from the distal centriole It is made up of 9 pairs of microtubules are originates radially around the two central filaments and it is surrounded by 9 coarse fibers Mitochondrial sheath organized around the coarse fiber that helps the middle piece Annulus is the juncture btw the middle piece and the principle piece The majority of the tail is made up of the principal piece and it goes all the way down to the end of the agellum The end piece is only made up of microtubules Unique aspects of spermatogenesis In female gamete supply is made before birth In male stem cells are made throughout life or called spermatogonia divide by the mitosis to make the primary and secondary spermatocytes the haploid spermatids and that is differentiating to make spermatozoa Clinical evaluation keep in mind that 24 week delays before the effects of the deleterious event this can happen because of heat stress fever exposure to toxins Can see this in the ejaculated sperm 612 weeks is needed for normal spermatogenesis to back able to go back to the deleterious event Cycle of the seminiferous epithelium This is the progression through the complete series of stages at a location along a seminiferous tubule Time is needed for this progression it is equal to the cycle and it different for each species There are 4 or 5 layers of germ cells inside the microscopic crosssection of the seminiferous tubule Each layer is a generation and because of the intercellular bridges the generation is a cohort of cells that makes as synchronous group Stages review spermatogonia primary 1 degree spermatocytes secondary two degree spermatocytes spermatids spermatozoa Recap GnRH LH testosterone is secreted in pulses during a couple hours FSH is released in smaller pulses for a longer period of time Spermatozoa is made by the testes and this process is called spermatogenesis and this has to have 59 weeks depends on species of sperm mad each day is independent of the ejaculated Stored in the epididymis is the spermatogenesis and Spermiogenesis that happens continually
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'