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Phys Repro Luteal Phase

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isabellepjk's version from 2017-04-28 12:54

Luteal Phase On

Question Answer
Luteal phase- what is the start of metestrus?Lack of estro. abolishes estrous behavior --> end of estrus, so start of metestrus.
What starts the luteal phase?After the LH surge has already induced Lutenization in Granulosa and THeca cells, the production of estrongen declines rapidly and progesterone increases slowly
Luteal phase- when does diestrus begin? How long does this takeCorpus hemorrhagicum gradually luteinizes into the corpus luteum. This is the start of diestrus
takes 4-6 days
What does the corpus luteum contain? What are the cells from?Some yellow fat and the two kinds of mature lutein cells
Small lutein (from theca cells)
Large lutein (from granulosa cells) cells.
During which part of the corpus luteum phase are small lut. cells active? Large Luteal cells? What do both types of luteal cells make, and why?Small= early CL phase.
Large=late CL phase.
Both produce PROGESTERONE, because it prepares the endometrium for a potential pregnancy.
How do progesterone levels affect the hypothalamic centers?
What is important about the result?
Inc progesterone will lower but NOT inhibit the tonic/surge centers-->
GnRH released in low frequency/low amplitude pulses -->
low level pulses of LH and FSH
LH pulses are necessary to keep the CL viable
FSH and LH pulses are sufficient to initiate folliculogenesis during diestrus, called follicular waves
What happens with follicular waves (low level GnRH release during luteal phase) in polyestrous domestic animals?During met/diestrus, basal GnRH/FSH-LH pulses induce cohorts of 1* follicles to grow (RECRUITED FOLLICLES),
Many become atretic.
Some may start to produce estrogen again (selected follicles) and many become atretic.
1/several (mono/polytocous) recruited follicles grow to antral follicles (dominant) and produce lots of estrogen, but only if they are not in the presence of progesterone (so, not in diestrus) will this lead to an LH surge (b/c progesterone inhibits surge center) so only after luteolysis can the surge respond to the recruited/selected follicles estrogen conc.s
What happens at the end of the Lutein phase to a livestock non-gravid uterus?Starts for produce pgf2a which reaches ovary via uterine vein/ovarian artery (bypass lung metabolism) and the PG F2alpha leads to APOPTOSIS of luteal cells--> CL regression--> progesterone dec= end of diestrus
end of diestrus/luteolysis in primates/carnivores. Not preg, what happens?PGF2alpha produced by CL!! (NOT UTERUS LIKE IN LIVESTOCK.). so then the PGF2alpha causes apoptosis of CL cells and dec of progesterone= end of diestrus
How does diestrus end/proestrus start?Progesterone decrease lifts the suppression on GnRH release so the GnRH pulses increase again in frequency/amplitude --> FSH and LH pulses increase and a new cycle can being with proestrus
what does oxytocin have to do with luteolysis? (comes from where for who, and does what?)oxy from large luteal cells in livestock, oxy from post pituitary in primates/dogs. OXY INITIATES THE PG F2alpha release! In some species, like sheep, oxy and PGF2a are release in pulses
when is the only time luteolysis can occur, and what makes this limitation possible?PGF2alpha receptors only high in LARGE luteal cells, which are the LATE diestrus cells...so luteolysis can only occur during late diestrus
what if you are a doc, and you want to make luteolysis happen?you can inject exogenous PGF to induce luteolysis, but it's only effective during mid-late luteal phase (b/c receptors only on Lg. luteal cells)
how can an endometritis cause a permanent anestrus/diestrus? in who?in rumi/pigs (NOT MARE) the endometrium would be the thing to produce the PGF2alpha, but it is diseased, so it doesnt produce the PGF2alpha, so no luteolysis is stim, so permanent CL continues to release progesterone--> stay in diestrus
Why would you want to induce luteolysis in vet med?for early gestation, abortion, parturition, synchronize herds, rid uterine infections (contraction of uterus helps move out infection)
what would happen if you injected progesterone into an animal? why would you do that?would stop regular cycle/encourage diestrus. Use as a birth control to prolong the cycle, keeping the animal from going into heat, to synchronize herds, or to maintain pregnancy
What is happening to the endometrium during follicular phase? (pro+estrus)PROLIFERATIVE PHASE. under ESTROGEN, prolif of the endo. inc thickness, hyperemia and swelling of vulva, endometrial and cervical glands secrete thin, string-forming mucus.
what is happening to the endometrium during luteal phase? (met+die)SECRETORY PHASE (biggest here). under PROGESTERONE growth of spiral arteries--> inc blood supply--> swelling of endo. with inc secretory activity, accumulation of nutrients (uterine milk)--> READY FOR IMPLANTATION/ATTACHMENT
what happens to the endometrium during the luteolytic phase?MENSTRUATION/REGRESSION. luteal phase--> BVs vasospastic--> necrosis of endometrium. in primates, this leads to desquamation/external bleeding (menstruation). other domestic animals absorb rather than desquamate their endometrium, either way they are regressing.
what is happening when a dog has external bleeding?NOT menstruation, it's massive prolif of BVs during PROLIF phase will cause some bleeding.
effect of estrogen on overall animal?growth/maintenance of primary and secondary female sex charateristics
effect of estrogen on uterus?prolif of endometrium, mucus
effect of estrogen on oviducts?prolif of glandular tissue and CILLIATED CELLS, INC CILIA ACTIVITY
effect of estrogen on vulva/vaginahyperemia, swelling, mucus
effect of estrogen on mammary glanddeposition of fat, prolif of stroma and duct system
effect of estrogen on skeletonINC OSTEOBLASTIC ACTIVITY and mineralization (so during menopause, dec in this causes possible osteoporosis)
effect of estrogen on metabolismslight inc protein synth, inc fat deposition/ SQ tissue
effect of estrogen on b/h?initiates sexual receptiveness
effect of progesterone on uterus?stim secretory activity of endo. glands, dec myometrial activity= progesterone block
effect of progesterone on mammary gland?develop mammary lobule and alveoli
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Gestation and parturition

Question Answer
what is imperative for the establishment of pregnancy and maintenance of corpus luteum?PROGESTERONE!!! (so luteolysis must be avoided, b/c CL is making the progesterone)
what would happen if animal preg and progesterone drops?endo. would undergo regression--> interrupt nutrient supply and beginning attachment process between conceptus+endomet= ABORTION
before conceptus attaches (2-4 weeks AFTER ovulation) how does it prevent itself from being aborted?conceptus produces signals to maintain CL, therefore progesterone production. It does this by inerfereing with endometrial PGF2alpha release
most important hormone to maintain preg? where is it produced?PROGESTERONE. first in the CL, then later in preg the placenta contributes or takes over the production.
what three things does progesterone do during preg?(1) maintain secretory activity/perfusion of endometrium. (2) dec uterus tone and inc cervix tone= PROGESTERONE BLOCK. (3) prepares mammary gland during late preg.
what is the MOST IMPORTANT event initiating parturition?inc in FETAL CORTISOL production, which leads to progesterone withdrawl (b/c it stims placenta enzymes to convert proges into estrogen)
what sends the initial signal to end gestation? how? Saftey measures to make sure this doesnt happen too early?FETUS gives of massive CORTISOL release. the fetus makes the CRH+ACTH during mid/end gestation (maybe stress b/c space limitations). also the adrenal cortex matures late (prevent from happening sooner, genetically controlled) so fetal cortisol release occurs only during last few days of gestation. no neg feedback cortisol-->ACTH
the fetal cortisol goes WHERE first?PLACENTA.
how does the cortisol affect the placenta?stims 2 steroid hormone enzymes to convert PROGESTERONE into ESTROGEN! inc estro and dec proges= removal of progesterone block
once the cortisol has caused placenta to convert proges into estrogen, and estrogen is inc, what effects does estrogen have? (3, general)(1) prepares myometrium to become contractile (2) inc lubrication (3) stim synth of placental PGF2alpha/ E2(estrogen)
how does estrogen specifically affect the myometrium?the # gap junctions and the myometrium INC--> single unit type sm. mm to facilitate coordination of contractions. also stim synth of of contractile proteins (Actomyosin) and inc in oxytocin receptors (PREPARES MYO. TO BECOME CONTRACTILE)
how does estrogen effect lubrication?sim mucus secretions of cervix to lubricate birth canal
what are the effects of PGF2alpha and E2 (estrogen) during parturition? (4)(1) initiates regression of CL (withdrawl progesterone) (2) relax/dilate cervix (3) inc intracellular Ca++/myometrium (initiate CONTRACTIONS) (4) in SOME species, the CL produces the hormone RELAXIN (which inc markedly with PGF2alpha induced final luteolysis apprx 10-14 hrs prior to birth. other species, gradual relaxin inc during last weeks of gestation)
what are the effects of relaxin? (2)(1) relax pelvic ligs and mm (2) separation of pelvic symphysis ---> both facilitate expansion of the birth canal
what is involved in stage one of parturition?initial myometrial contractions induced by PGF2alpha push fetus slowly towards the internal os of the cervix. in LG SPECIES, fetus turns from its ventral to a dorsal position.
what is the delivery position/what is it called in large species?"diving position" which is an anterior presentation (back is dorsal, head is caudal, forelimbs foreward)
what is the delivery position in small species?fetus presents in either anterior or posterior postion while being pushed slowly towards the cervix
what is stage two of parturition?as fetal membranes/legs/head/butt push against/enter cervix, pressure receptors stim and initiate FERGUSSON REFLEX/OXYTOCIN RELEASE which initiates rhythmic myometrial contractions (and abdominal mm too)==> EXPULSION OF FETUS
what is stage three of parturition?delivery of FETAL MEMBRANES through sustained surges of PGF2alpha (from placenta).
when are the fetal membranes delivered in species that litter bear? single bear?litter= with or after each fetus. single= up to several hours after fetus.
what is PUERPERIUM? what happens during it?period of uterus involution and regeneration (6 days-weeks). attachment points of fetal membranes slough off, new epithelium forms= healing of endometrum. myometrium contracts= size reduction.
what hormone is released during the last days BEFORE parturition? what does it do?PROLACTIN, it induces lactogenesis and induces maternal b/h.
what is the order of hormones for parturition?CEPRO! Cortisol--> estrogen--> PGF2alpha--> relaxin--> oxytocin.
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