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Repro
Test 3
| Term | Definition |
|---|---|
| 3 requirements to meet before sperm can be produced. | 1) Adequate GnRH release (high freq./low amp) 2) FSH/LH from Anterior Pituitary 3) Secretion of gonadal steroids (High conc. test in testis, low conc. test in systemic blood) |
| What is the frequency and amplitude of GnRH from the tonic center in a male? | High frequency, low amplitude pulses |
| Are LH patterns different or similar to GnRH secretion patterns? | Similar -- follows pattern -- released for 10-20 minutes, 4-8 times per day |
| Is FSH secretion higher amplitude or lower amplitude than LH? Why? | FSH is lower than LH -- due to inhibin from the testes |
| Are FSH secretions longer or shorter than LH? Why? | FSH longer than LH -- FSH has a longer 1/2 life |
| What is inhibin? Where is it released from? | Hormone that provides negative feedback against FSH -- testes and ovaries |
| Where does LH bind? | To Leydig cells |
| Why should testosterone match LH secretion? | Because LH binds to Leydig cells -- which releases testosterone |
| What is the FSH peak not sharp? | Due to its half life |
| Does testosterone peak before or after LH binds to leydig cells? | After LH binds |
| Is LH a protein hormone or steroid hormone? | Protein hormone |
| When LH binds to membrane receptors on Leydig cells, what is converted to testosterone? | Progesterone |
| Is testosterone released in long, consistent waves or short pulses? | Short pulses |
| Why is it important to have LH pulses instead of consistent release? | High concentration of testosterone is important for spermatogenesis, but leydig cells become refractory to high concentrations of LH which leads to low testosterone (receptors downregulate) -- so it needs slow stimulation over time |
| Why is LH the main negative feedback hormone rather than testosterone? | Testosterone is quickly diluted in blood and has a short half life (cant have strong negative FB on GnRH). If released in high concentrations, neg FB of GnRH/LH/FSH (negative FB on spermatogenesis--not good) |
| What cells are FSH receptors on in a male and female? | Sertoli and Granulosa |
| What cells are LH receptors on in a male and female? | Leydig and Theca |
| What enzyme converts testosterone to Estrogen? | Aromatase |
| What are two ways estrogen can be produced in a male? | By using aromatase within the Leydig cell to convert testosterone to estrogen -- When testosterone is released from Leydig cell to blood, Sertoli cells can convert it to estrogen |
| What are two things that sertoli cells convert testosterone into? | Estradiol and DHT |
| What is the role of estradiol that is released from Sertoli cells? | Negative feedback of GnRH -- more control on LH |
| Where is inhibin produced in a male? | In Sertoli cells |
| What is the theory for making estrogen? | 2-cell-2-gonadotropin theory |
| What is the dominant structure in the Follicular Phase? What is the dominant hormone? | Follicle is dominant -- estradiol is dominant hormone |
| What is the dominant structure in the Luteal Phase? What is the dominant hormone? | Corpus Luteum is dominant structure -- Progesterone is dominant hormone |
| What day does ovulation occur in estrous? | Day 0 |
| What day does menses occur in menstrual cycle? | Day 0 |
| Compare what happens on day 0 of menstrual vs estrous | Menses - men |
| What % of estrous is follicular and luteal? | 20% follicular, 80% luteal |
| What % of menstrual is follicular and luteal? | 50% follicular, 50% luteal |
| What is the difference between estrus and estrous? | Estrous (adj.) - cycle -- series of predictable events that begin at Estrus and end at end of subsequent Estrus Estrus (noun) - period of sexual receptivity |
| What is Estrus greek for? | Gadfly, Sting, Frenzy |
| What is Gadly, Sting, Frenzy? | Animal acts as if they have been bitten and then exhibits wild behavior when in estrus |
| What is the average length of estrus? What is it dependent on? | 20 days, but species dependent |
| What are 3 categories of Estrous? | Polyestrus, Seasonal polyestrus, monoestrus |
| What is Polyestrus? | uniform distribution throughout year, may become pregnant regardless of season |
| What animals exhibit polyestrus? | Cow, pig, queen, rodent |
| What is seasonal polyestrus? | Cycle during certain seasons -- cluster of estrous cycles (short day breeders and long day breeders) |
| When do short day breeders mate? What are examples of these animals? | Fall -- ewe, doe, elk, nanny |
| When do long day breeders mate? What are examples of these animals? | Summer -- mare |
| What is monoestrus? | One cycle per year or 3 cycles per 2 years |
| What are examples of monoestrus animals? | Dogs, wolves, foxes, bears, domestic canids |
| What is unique about the estrus of monoestrus animals? | Have estrus that lasts several days -- time between ovulation and fertilization |
| Why do dogs have time between ovulation and fertilization? | So the dog can mate with multiple males |
| What events does the follicular estrous phase consist of? | Regression of CL to ovulation (Proestrus and Estrus) |
| What events does the luteal estrous phase consist of? | Ovulation to CL regression (Metestrus and Diestrus) |
| What is proestrus? | Progesterone declines do to CL regression -- 2-5 days -- transition from P4 to E2 dominance -- formation of ovulatory follicles and estradiol secretion |
| Does estrogen affect progesterone or does progesterone affect estrogen? | Progesterone affects estrogen |
| Where is PGF-2 alpha from in most animals? | Uterus |
| What is estrus? | Sexual receptivity and mating period -- major physiological changes in tract -- peak estrogen |
| What is the different between the female mounting and the female being mounted in estrus? | Female who mounts in in proestrus -- female being mounted is going to ovulate in 12 hours (is in estrus) |
| What is metestrus? | CL formation and beginning of progesterone secretion -- both estrogen and progesterone high |
| What is Diestrus? | Longest stage of cycle -- CL fully functional, Progesterone peaks, ends with luteolysis -- progesterone prepares uterus for possible pregnancy -- lasts 10-14 days |
| If pregnancy occurs in animals, what estrous phase continues? | Diestrus |
| What animals are induced ovulators? | cats, alpaccas, llamas |
| What do induced ovulators need to ovulate? | Vaginocervical stimulation |
| What stimulates behavioral estrus in induced ovulators? | Increased levels of estrogen stimulate this |
| What does vaginocervical stimulation activate? | Activates a neuroendocrine reflex resulting in a GnRH release -- results in LH surge -- ovulation -- progesterone will maintain pregnancy if necessary |
| What is different about a queen's estrous cycle? How do P4 levels look? | They only have estrus and proestrus -- P4 is always low unless pregnant |
| In a dog, what is unique about FSH? | An FSH surge occurs directly after ovulation -- always recruiting new follicles |
| In a dog, what hormone rises during anestrus? | Inhibin and Estrogen (estrogen rise signals follicular development) |
| What is diapedisis/pseudomenstration? | Uterine vessels leaky due to elevated estrogen -- bleeding in proestrus period (not same mechanism as menses -- hormone withdrawal) |
| How can you determine the day of a cycle in rodents? | By doing a vaginal cytology -- when in estrus, high population of cornified epithelium |
| If there is no mating with rodents, what happens to CL? | CL is non-functional, lasts 2 days, cycle moves to diestrus |
| If there is mating with rodents what happens to CL? | CL maintained by prolactin for 12 days = pseudopregnancy -- no pregnancy, CL regresses -- pregnancy, maintained by placental P4 |
| How is prolactin formed? | By mating |
| What is anestrus? | Ovaries inactive, no functional CL, no ovulatory follicles |
| What are 3 reasons for anestrus? | 1) insufficient GnRH -- 2) lactational anestrus -- 3) seasonal anestrus |
| What is the cause and effect of insufficient GnRH and anestrus? | Pregnancy causes -- progesterone high (from CL and placenta) -- negative FB on GnRH neurons -- No FSH/LH -- No follicular growth -- No ovulation |
| What is lactational anestrus? | type of postpartum anestrus -- often used to synchronize estrus -- allows uterus to repair before estrus -- suckling activity inhibits FSH, LH -- nervous system thought to control |
| What are two exceptions of animals with lactational anestrus? | Tammar Wallaby and Beef Cattle |
| What is unique about the Tammar Wallaby? | It has embryonic diapause -- embryo formed but stays in blastocyst phase unti lactation is complete |
| What is unique about beef cattle and lactational anestrus? | Lactation alone does not effect estrus -- other factors may be involved such as visual encounters and olfactory and auditory encounters with offspring |
| What type of cattle does not experience lactational anestrus? | Dairy cattle -- calf is immediately removed, usually milk mother for period of time, dry period, then breed again |
| What is seasonal anestrus? | prevents pregnancy from occurring during period of low food availability -- high temperature causes low sperm count -- embryo can experience heat shock |
| What are animals that cycle in the fall? When do they give birth? | Short day breeders -- birth in spring -- sheep, deer, elk |
| What are animals that cycle in the summer? When do they give birth? | Long day breeders -- birth in spring -- mare |
| What do animals that have seasonal anestrus have? | Photoperiod |
| What does photoperiod control? | the transition between cyclicity and anestrus to cyclicity |
| What is the onset of seasonal cyclicity similar to? | Puberty -- dependent on GnRH |
| What chemical can stimulate or inhibit GnRH? | Melatonin |
| How does high melatonin affect long day breeders and short day breeders? | High melatonin in long day breeders causes low GnRH -- High melatonin in short day breeders causes high GnRH |
| What does GnRH amplitude and frequency look like in anestrus? | Low amplitude, low frequency |
| Is melatonin high when it is dark or light? | Dark |
| If you inhibit your pineal gland, is melatonin high or low? | Low |
| When you do not inhibit your pineal gland, is melatonin high or low? | High |
| What day of the menstrual cycle does ovulation occur? | Day 14 |
| Does menstrual cycle have a defined period of sexual receptivity? When? | No -- they don't |
| How is menses defined? | Sloughing of endometrium to exterior -- menstrual period |
| How long is the average menstrual cycle? | 28 days |
| What effect does estrogen have on endometrium? | High E2 makes endometrium THICK |
| What effect does progesterone have on endometrium? | |
| What two phases of menstrual cycle are part of follicular phase? How long are each of these? | Menstrual (5 days) and Proliferative phase (9 days) |
| What are characteristics of menstrual phase? | Contraction/relaxation of spiral arteries, shedding of necrotic endometrium, decreased steroid production, release inflammatory mediators, PGF2alpha, cytokines, NO released, thin layer of epithelium remains |
| What are characteristics of proliferation phase? | Endometrium increases thickness, re-epithelialized by day 4-7, endometrial glands increase in size (straight and narrow) |
| What phase is part of the luteal phase of menstrual cycle? How many days does it last? | Secretory phase (14 days) |
| What are characteristics of secretory phase of menstrual cycle? | P4 increases dramatically, E2 increases, further enlargement of endometrium, glands increase in size and number (highly coiled and secretory), if no pregnancy = CL regression |
| What is menopause? What is is analogous to in the estrous cycle? | No cyclicity, ovaries not producing E2, similar to pre-pubertal state -- analogous to anestrus |
| What is amenorrhea? | Absence of menses during reproductive age due to lack of energy balance, stress, fatness/nutrition issues |
| What is lactation regulated by? What does this hormone affect? | Prolactin -- increase in prolactin causes decrease in GnRH frequency and amplitude |
| What is used as an alternate form of contraception after birth? | Lactation -- not that effective (only 75%) |
| In the surge center, what effect does E2 have? Frequency/Amplitude levels? | Positive FB -- high amplitude and frequency of GnRH |
| Positive FB of estrogen to surge center only works in absence of ______? | Progesterone |
| How does estrogen affect tonic center? | High levels provide negative FB to tonic center -- keeps amplitude low and frequency high (GnRH/FSH/LH) |
| What effect does high progesterone have on hypothalamus? | High progesterone in Luteal Phase provides negative FB to hypothalamus only (low amp/freq of GnRH) |
| During the follicular phase, which hormones are low and which are high? | Luteolysis occurs, so progesterone is low -- negative FB on hypothalamus removed -- FSH/LH increase -- estrogen dominant (follicles present) |
| What two hormones are high during follicular development? | Inhibin (reduces FSH) and Estradiol (Preovulatory LH Surge) |
| What is the cycle of mature oocyte formation? | Primordial -- Primary -- Secondary -- Tertiary |
| When does oogenesis begin? When do they fully mature? | Begins during fetal development (approximately 20 weeks, antral after 26 weeks). Fully mature after LH surge. |
| How does LH affect an oocyte? | Reduces egg from 2n to 1n = reduces chromosome # |
| What is folliculogenesis? | Oocyte develops within the somatic cells of the ovary (granulosa and theca) -- matures into fertilizable oocyte |
| If oogenesis and folliculogenesis don't work together, what happens? | Repro failure |
| Does granulosa or theca develop first? | Granulosa first then theca second |
| What types of cells are primordial cells? | Squamus |
| What stage do primordial follicles enter into until LH surge occurs? | Entered diplotene of prophase 1 |
| How many cells does a fetus begin with? What is that number at birth? | 6-7 million -- 400,000 at birth |
| By puberty, how many eggs are lost? At age 37? Age 50? | 90% lost -- approx 25,000 at age 37 -- 1,000 at age 50 |
| How many eggs do you actually ovulate in your reproductive yeras? | 400 |
| What cells are primary follicles made of? | Cuboidal (granulosa) - 1 layer |
| What cells are secondary follicles made of? | at least 2 layers of granulosa cells -- no fluid/antrum -- start to form theca layer |
| What cells are tertiary follicles made of? | 2+ layers of granulosa, theca will form 2 layers (theca interna and externa) -- antrum formed |
| Are FSH/LH present in primordial cell recruitment? | No |
| Which cell recruitment phase is when gonadotropin goes from being idependent to dependent? | Primary follicle recruitment |
| When does cyclic recruitment begin to happen rather than initial recruitment? | During secondary follicle recruitment |
| What are the stages of recruitment from initial to cyclic? | Primordial (initial) -- Puberty -- Primary(Cyclic) -- Recruitment Secondary (Cyclic) -- Selection Tertiary (Cyclic) -- Dominance (potential to ovulate) |
| When do FSH receptors appear on granulosa cells? | During secondary follicle recruitment |
| When do LH receptors on Theca and RSH receptors on Granulosa appear? | During Tertiary Selection |
| What cells and receptors are present during dominance of cyclic recruitment? | FSH-R on Granulosa, LH-R on Granulosa and Theca |
| What is the 2-cell-2-gonadotropin theory responsible for? | Estradiol production |
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