chapters 5,7,8,9,10 AGSC 352
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This 25 page Bundle was uploaded by nicole l brown on Sunday October 18, 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 36 views. For similar materials see Reproduction Physiology in Agricultural & Resource Econ at Truman State University.
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Date Created: 10/18/15
Repro Dr Walter Rest of Chapter 5 chapter 7 and most of chapter 8 o Adrenal gland this is a glucocorticoids and cortisol 0 Cortisol is a steroid hormone and it is made in the adrenal cortex It starts the initiation of parturition it works with prolactin to initiate milk synthesis and it will also reduce in ammation 0 Hormones only work on specific cells 0 These special cells have certain receptors and can tell the hormone to act on that cell in the tissue that hormone is supposed to act on Each hormone has a special receptor and the halflife for each is different 0 The class of repro hormones the peptidesprotein o For the peptide hormones they have a small number of amino acid 3 a less number 0 Neurohormones that affect the AP is the GnRH is a peptide and it comes from the 0 Hypothalamus and this signs that the FSH and LH to release from AP 0 Oxytocin OT it is a peptide hormone that is made in the hypothalamus and it housed in the posterior pituitary The functions of this hormone is when milk is let down it stimulate uterine contractions during sperm and egg parturition and transport estrogen enhances the responsiveness of smooth muscle it is a Leutolytic in cow ewe and doe o Melatonin it is a peptide and it is located in the pineal gland in btw the cerebral hemispheres The epithelial cells inside the pineal gland make and secrete melatonin it is an antigonadotropic The nerve fibers have impulses from the retina to travel along the optic tract to the cranial cervical ganglion and they end in the pineal epithelial cells When this hormone is released is controlled by day length and its actions is to control of the seasonal breeder by the day length So for short days the decreased light then increases melatonin and that then decreased GnRH The long days is then increased light and decreased melatonin and increased GnRH O o For the protein hormone they are larger in size and have more than 200 amino acids 0 Steps of action 0 1 hormonereceptor binding this hormone well diffuse from the blood stream and attach with the receptor that matches the hormone 0 2 adenylate cyclase activation this activates the enzyme that is membrane bound adenylate cyclase and then bind to the Gprotein Because of step one then the adenylate cyclase is started This then converts ATP to AMP cAMPthis is called the second messenger inside the cytopplasm of cell 0 3 protein kinase activation this is when CAMP then activates a control emzyme that is inside the cytoplasm of the cell that the protein kinases target Then because of the kinases starts enzymes in the cytoplasm that then converts substrates into products 4 synthesis of new products these products that are made by the cell because of the protein kinases it is secreted Then the secreted products have specific functions that well enhance repro processes 0 Glycoprotein hormone these have carbohydrate moieties that are hooked to the backbone of the protein This has alpha subunit that is a common hormone It also has a beta subunit that is different btw hormones to be able to be specific in there action An example is the alpha subunit is LH and FSH in the horse whiles the beta subunit that is different The function for both This is called a second messenger because it stays on the outside of the cell These receptors for these messengers are on the plasma membrane from the cell The act of the hormone binding on outside of cell then tells another receptor in the cells to then carry out the action Think of a computer you can t put you hand inside the screen and move the mouse you have to use the mouse that then tell the curser to move across the screen Steroid hormones these are made from cholesterol and it can change at some carbons to be able to determine biologic nature The major classes that this hormone includes are androgens estrogens progestins The function of this hormone is to go into the cell and bind to the intracellular receptors then the hormone alters the gene transcription and the translation in nucleus Now the thought about the steroid hormones is that they have 2 methods of action and it also utilizes a membrane receptor using cAMP just like protein hormones The benefits of this action are it provides a faster response min and other methods for example nuclear receptors slower response hrs Lipid hormones it is the prostaglandins class the lipid molecules are then derived from the arachidonic acid it was discovered in the seminal plasma and the thought that it first came from the prostate gland In the concept of reproduction there are 6 prostaglandins PGF 2 alpha PGE 2 Feedback signals these feedbacks are the controls of the repro hormones The positive feedback is when one hormone signs the release of another hormone This then increase the levels of E2 and that action of increasing this hormone then signs the release of GnRH LH FSH The negative feedback is when on hormone stops or inhibits another from getting released The increasing P4 well inhibit the GnRH FSH LH release The FSH then well is stopped from being secreted from the AP Halflife of hormone this determines how long the different hormones well act Each halflife of each hormone are different and the rate that they are cleared from the blood stream determines the halflife The longer the halflife the longer the potential bio activity there function well give you a clue on how long there halflife is these different proteins are absorbed in the liver that are then eliminated by kidneys The hormones are inactivated in the liver this is done by the saturates double bonds The hormones then attaches to a glucuronide residue to produce water soluble so it can exist the body though the urine and it can also go out though the feces Hypothalamohypophyseal portal system portal vessel is When the blood supplies btW the AP and hypothalamus Important note the Posterior pituitary is Where the hormones are stored Repro Dr Walter Chapter 8 follicular phase 0 Follicular phase this contains the proestrus and estrus and it is the kick starter to the follicular phase is luteolysis This causes CL to become nonfunctional and it reduces progesterone by using the negative feedback on the hypothalamus The GnRH is then released at higher amplitude and frequency the FSH and LH are then released at higher concentration follicular development estradiol secretion 0 There are four event that take place in the follicular phase 0 Gonadotropin release for AF 0 It is the major secretion of follicular phase from the hypothalamus AP ovary o The hypothalamus then regulates cycle by production of the GnRH The tonic center is in charge of the basal secretions and that happens in small pulses the varying of the bursts and the how long it lasts and the quantity is called episodic profile The surge center is where the preovulatory release of GnRH to start the surge LH the positive stimulus for the surge this the is the threshold concentration of estradiol and this happens in the absence of progesterone o Follicular preparation for ovulation 0 Sexual receptivity or estrus 0 Ovulation 0 GnRH secretion it is before ovulation and this then the surge of GnRH is controlled by the high amount of estradiol and the low progesterone high estradiol is positive feedback while high progesterone is negative feedback The threshold for estradiol is reached due to production from the follicle The rest of the LH will surge is 10 times greater than tonic pulse 0 Follicular dynamics 0 Process of follicular growth and degeneration this occurs continuously throughout the cycle The antral follicles then develop is response to FSH and LH in the pig a small follicle is less than 3mm medium is btw 46mm large is greater than 6mm in the mare a small follicular is less than 10mm a medium is btw 1020 mm and a large one is bigger than 20mm 0 Antral follicles involves 4 processes 0 Recruitment emergence it is a group of small antral follicles that begins to grow and they secrete estradiol Most of the follicles in this stage well undergo atresia and the then they well degenerate and resorption before ovulation 0 Selection this is when the growing follicles that haven t gone through atresia are selected and they become dominant latter they could become atretic In monotocous species only one follicle is selected for example cow mare and woman Polytocous species more than one follicle is selected and they all well become dominant o Dominance These follicles well secrete increasing amounts of estradiol and inhibin this inhibits FSH from the AP Because of the follicle becoming dominant it well inhibit other follicles from growing because of the suppressed FSH it reduces the blood supply to nondominant follicles that well then go to the next stage 0 Atresia this involves more follicles than just the dominance one about 90 percent of follicles o This was first looked at in cows that us ultrasonography by examining ovaries on a regular basis that allows visualization of the changes in size and the number over time o FSH and LH This hormone has different effects on the follicles and secretion is controlled differently FSH is from the AP is released in small amounts and stimulates recruitment of the follicles the follicle well grow and secrete estrogen and inhibin and then FSH drops then a second rise in FSH might then occur in Diestrus if a second wave of recruitment occurs 0 LH its primary role is to promote the final growth and maturation of the dominant follicles and then it stimulates ovulation The frequency of the pulse changes the Metestrus and Diestrus are about 6 pulses per day this does not start the first wave in the follicle After luteolysis the progesterone then drops and the concentration of LH increases about 24 pulses per day 0 Regulation for FSH is controlled by estrogen and inhibin decreases and it is secreted by the growing follicle because of the negative feedback For LH controlled by the increase pulses of GnRH 0 Two cell two gonadotropin model this happens during the follicular development by the LH binds to the membrane receptors for LH receptors on cells of the theca interna this converts cholesterol to testosterone and then testosterone travels to the granulosa cells Then granulosa cells contains the FSH receptors when the FSH binds to the receptor it causes testosterone to convert to estradiol This process well continue until it reaches threshold that then causes preovulatory LH surge 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 Repro Dr Walter Reproductive cyclicity terminology and basic concepts Estrous cycle it is the physiologic events that occur btw periods of sexual receptivity after puberty This is predictable by watching for estrus heat and the start of subsequent estrus This process can only stop if the animal becomes pregnant lactation and some species the season of year this can also stop under inadequate nutritional conditions and stressful environmental conditions The behavioral events that happen during this phase are the sexual receptivity and copulation Estrus or heat or season is from the Greek word that means sting or frenzy Another word for this state is oestridae that comes from an insect that would bit cattle and the cattle would move their tails this is also a sign of sexual receptivity in mammalian females 0 Estrus heat is the noun use of the word It is the sexual receptivity and it is used to say that someone is in estrus 0 Estrous if the adjective use of the word It is when estrous cycle is period from one estrus to another So you can say the animal is in the estrous cycle 0 Estrual is the adjective that is used to id the condition that is related to estrus Types of estrous cycles based on frequency of occurrence throughout the year 0 Polyestrus these are animals that display estrous cycle the same and it is distributed throughout the year that is without marked seasonal in uence Cattle swine rodents 0 Seasonally polyestrus when female exhibit multiple estrous cycles that is during specific season of the year this happens in sheep goats mares deer elk 0 Monoestrus this is in animals that display only one period of sexual receptivity during a year this happens in dogs wolves foxes bears Phases of estrous cycle 0 It is divided into two distinct phases it is named after the dominant structure that is present ovary during each phase of the cycle 0 Follicular phase it is the period from regression of the CL to ovulation it is relatively short about 20 of the cycle The primary structure is large growing follicles that secrete estradiol 0 Luteal phase it is the period from ovulation to CL regression it is longer then about 80 of cycle The primary structure of this phase is the CL and the primary hormone is progesterone Stages of estrous cycle each is then divided into the follicular and luteal phase 0 Proestrus follicular phase it begins in the progesterone and it declines because of the luteolysis the tear down of the CL This stage stops on the onset of estrus it lasts 2 to 5 days and it can depend on species It is characterized by the major endocrine transition where the progesterone dominance to the estradiol dominance the FSH and LH are responsible for this dominance tug of war During this stage the antral follicle is ready to ovulate and the female tract then prepares for estrus and mating to enter the system Estrus follicular phase this stage takes a while to develop and the behavioral symptoms are visible increased locomotion increased vocalization nervousness mounting and standing to be mounted The next step from this first start of the stage are the standing estrus which is when the female is ready to mate with the male this can also be displayed by something called lordosis which it the mating posture How long this usually takes depends on species The hormone that is most used is estradiol and that induces profound behavioral alterations and this can cause major physiological changes in the repro tract Metestrus luteal phase this is the period btw ovulation and the formations of the CL These two hormones estradiol and progesterone are in low concentrations in early stages This ovulated follicle then undergoes cellular and structural changes that results in intraovarian in the endocrine gland that well then turn into the CL this process to transform is called Latinization The hormone progesterone is secreted in the late stages of this process it is about 2 to 5 days that are required after ovulation for CL to produce a lot of this hormone Diestrus luteal phase this is the longest stage in estrous about 10 to 14 days The CL is then fully functional and the dominant hormone progesterone is used by the uterus for the early embryonic develop And then not estrous behavior displayed This process ends when CL is destroyed this is down by the luteolysis Ovulation Menstrual cycle it is the physiological events that occur btw menstrual periods The shedding of the endometrium it has no defined period of sexual receptivity this cycle begins with menses and at the middle of the cycle ovulation begins How long this usually takes is about 28 days The follicular phase is only half of the cycle and during follicles develop it produce high level of estradiol and this causes LH to surge and this end product is ovulation about 14 days long The estrous cycle in the follicular phase is 20 of less Dog has differing stage sequence where anestrus lasts about 20 weeks proestrus this is the beginning of the estrous cycle because of the drop of FSH that is then caused by negative feedback from inhibin this is secreted from the develop Follicle estrus and Diestrus This species doesn t develop Luteal tissue that happens after ovulation during estrus The decrease of estradiol and the increase of progesterone are showed by the receptivity to the male The surge center releases LH and ovulation occurs 23 days this is when fertilization is about 4872 hours after ovulation This allows for superfecundation more than one ovulation is produced then more one oocyte is produced when single estrus happens This means that one liter from one female can have babies from multiply dads The Metestrus is not as defined in this species the initial development t of luteal tissue that happens during estrus right after ovulation Cat there stages of estrous cycle proestrus estrus postestrus Diestrus anestrus This species needs mating to occur to kick start ovulation If a female doesn t get prego she well go back to postestrus for a few days and then she returns to estrus The time frame that estrus lasts in the female 9 days every 17 days Gestation of the fetus last about 60 days Anestrus this is when females that do not exhibit estrous cycle and the ovaries don t work so no follicle or CL present This is caused by an lesser amount of GnRH True anestrus it is caused by not enough hormonal stimuli this can be caused by poor nutrition stress lactation season pathology Apparent anestrus it is the failure to detect and or recognize female is pregnant This improves the pregnancy detection method and the estrus detection Gestational anestrus it is the lack of cyclicity and that equals to major clue that the female is pregnant The increases levels of progesterone from the CL and or the placenta the hypothalamus has a negative feedback and the result is no follicle maturation and the expression of estrus and then the surge of LH The levels of progesterone decreases before parturition and the estradiol increases Different species have differences in postpartum cyclicity Seasonal anestrus it evolved to be able to prevent pregnancy during the seasons when survival of the fetus would be last on the priority list In the spring is the most popular time for birth of an animal because of the abundance of nutritional conditions This process is controlled by photoperiod and the first ovulations after this anestrus is silent ovulation Seasonal cyclicity it is the reduction in frequency of GnRH secretion and this happens before breeding and it needs sufficient GnRH amount to cause SP to respond Long day breeder for example mare Because of the increase day length in spring causes cycling and the increased light can cause stimulation of kiss neurons So the more amount of light the mare is exposed to the less melatonin and the kiss neurons are started and then more GnRH is made The length of gestation for this species is 11 month Short day breeder is in the species of sheep goats elk and deer This happens in the fall and the length of gestation is about 5 months because of the decreased light the kiss neurons are stimulated So the less light more melatonin and kiss neurons get started and more GnRH Lactational anestrus this happens in females that nurse their young The exceptions to the rule are the mare and alpaca is displayed in cow and it is caused by the degree of sucking and the cyclicity can return is sucking two times a day or more happens This cycle does not happen in the sow the causes for this anestrus is visual encounter with offspring olfactory encounter with baby auditory encounter with baby But this is not started by the stimulation of teat as previously though To kick start cyclicity you can replace the calf with someone else s baby but this doesn t really happen in the dairy cow they take the calf right after birth Nutritional anestrus this is caused by negative energy balance because of the low intake of energy or protein The pulses of GnRH are not present in this anestrus because the amount of secretion of gonadotropins is not enough to cause a change so the ovaries don t work This process is common in primiparous females which means they gave birth for the first time These females are normally young and they are still growing the energy that is needed for growth and lactation It is difficult to manage If enough nutrition is increased to a normal level then the estrous cycles well start back up Amenorrhea is the anestrus for humans it is caused by menopause poor nitration lactation The menopause is caused be the regression or the follicles within the ovary because the estradiol contraction decreases then progesterone secretion is no longer happens this normally follows ovulation The energy status can cause the lack of cyclicity when the body is using all its energy to maintain its necessary systems it doesn t need to reproduce Lactational is caused by high prolactin and nutritional strain and the average time that this can take place is 6 months past partum 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 Repro Dr Walter 101 breeding soundness evaluation 0 Breeding soundness examination BSE o This should happen 45 to 60 days before the breeding season This doesn t guarantee fertility but you can see animals that are having problems with their repro process Herd that used this had 8 increase fertility o Males low libido can t be detected using this 0 Helpful for reproductive potential ranges from basic exam depth The results can show what needs to be improved in the male chance of fertilizing oocyte and female chance of getting pregnant carry and delivering a baby 0 Males 0 Looking at the past of the animal is helpful to look at libido mating ability what type of mating systems has worked in the past What the offspring looksuccessful Also look for genetic disorders 0 The structural soundness of the male you can look a body condition general health feet and legs eyes and teeth The reproductive anatomy scrotum testicles testicular circumference seminal vesicles and prostate and ampulla penis The semen quality of the male presence of sperm motility morphology foreign debris o A male with a poor body condition can produce lowquality semen not aggressive breeders 0 Feet and legs boars and stallions have dejenerative joint disease and osteochondrosis or they have arthritis Look at structural incorrectness any problem with movement well decrease mobility of the male harder to get to females and mount and can have the male have pain during copulation These problems with joints and structural can be heritable o Repro anatomy 0 External and internal examination 0 Testes and scrotum measure and palpate to look at problems and size look for prior injuries to that area and look for abscesses thickening and irritation The area should be symmetrical firm slightly resilient different breeds minimum scrotal circumference is 3033 cm for yearling bulls minimum testes size in 67 month boar is 457 cm 10 12 month boar is 5585 cm 0 Epididymitis this area should be symmetrical The head is usually firm tails tense and it is kind of large 45 cm in adult boars 0 Problems with testes epididymis 0 The head of epidymis is the spermatic granuloma this comes from blindended efferent ductules to spermiostasis to in ammation to granuloma Epididymitis Asymmetric testis Epididymal cysts Dermatitis of scrotal skin This can happen by trauma frost bite exposure This can be seen by the crusting and exudation of the skin this happens because of the chronic irritation and in ammation caused by mites Scrotal circumference This is a great indicator for sperm producing ability An accurate measurement needs testes to be pushed ventrally There is a specific tape used for measurement This circumference is related to the age the animal reaches puberty sperm production and the number of sperm in ejaculate In females it is the age the animal reaches puberty and the milk production It is genetic There are standards for each breed Nonpendular scrotum The width and length of the scotum can predict the sperm producing capabilities In stallions the average width is 456 cm the height is 565 cm and the length is 85 11 cm Volume ml it is equal to 05233 X width X height X length The total volume is each testes vol added together The daily sperm output DSO is determined by the testicular volume TV DSO stands for billions spermday which is equal to 0024 times TV 126 Repro anatomy Prepuce or called the sheath look for swelling bruising laceration pooling of urine debris semen Penis should have a normal structure free from laceration and bruising It shouldn t have any growths present or a hair ring hair clumps together and cuts of blood supply Examination of penis at time of ejaculation Persistent penile frenulum this causes the penis to have or be called a fish hook this happens when male goes to mate Surgery can fix this but this is heritability Papilloma it looks like a wart that can be removed but it can come back Corkscrew deviation in bulls natural breeding the bulls corkscrew during ejaculation But if the bull corkscrews too early it well prevent him from entering the female During electroej aculation this can happen and the male can get used to corkscrewing early so if you were to have the bull switch to natural mating he needs to be watched carefully Problems Persistent frenulum is when a fibrous tag btw prepuce and penis o Penile hematoma when the penis ruptures during trauma to the erect penis 0 Internal examination 0 Rectal palpation the two vaginal rings should be eval size opening Look at the size of the deferent ducts and the testicular artery pulse the presence of adhesions lesions herniation of the viscera By palpating you can look at the accessory organs seminal vesicles which are an infection of the seminal vesicles this can be found by palpation 0 Semen collection 0 Methods of collection 0 Artificial vagina a container catches semen but for the use of boars and stallions it needs a filter at the opening to separate the gel fraction out of the semen 0 Hand collection boars pressure is used at the distal portion of the glans penis 0 Electroej aculation boars rams bulls good for dangerous to handle or difficult males Bulls and boars semen collected is the same as other methods But in rams there is a loss of concentration from this method In boars they have to be anesthetize and placed in a lateral position recumbancy with the rectum cleaned out they have a exteriorize penis probe is inserted in rectum and the pulses begin for 45 sec intervals with 510 sec rest periods most well ejaculate after 45 stimulations Rams just have to be put in the lateral recumbancy the penis is extruded and held with gauze they have to be slowly stimulated most well ejaculate after 1 stimulation and a rectal massage with probe but you can only try this twice if the first one didn t have them ejaculate o Bulls a restrained rectal probe is inserted and this effects the nerves that innervate the repro tract and this causes erection protrusion ejaculation This process takes less than 3 minutes 0 Daily sperm production 0 This is the total spermatozoa produced per day by both of the testicles This is measured by the total of spermatozoa that is ejaculated into an AV with daily ejaculations for about 10 days to 2 weeks 0 Semen evaluation Look at concentration volume motility morphology total number daily sperm output 0 Results of BSE o If any major issues that show up through the BSE process then the male should be castrated 0 Problems that can be treated are injuries infections arthritisjoint disease supplements and antiin ammatories 0 But this process does not guarantee that the breeding season well be successful this is only used to predict how a male could perform estimate number of females that could be breed from one male this doesn t indicate libido in a male
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