_________ from the ________ is essential for pregnancy.
Mid-gestation onward, which species main progesterone source is still the CL? (5)
goat, dog, cat, pig, rodent
Mid-gestation onward, which species main progesterone source is the placenta? (5)
sheep, cow, mare, primate, guinea pig
What are the only 2 species that do not a a fall in progesterone just prior to parturition?
primate, guinea pig
In species that switch to placental progesterone, what is the clinical implication of this?
giving lute in the third trimester WILL NOT terminate the pregnancy, as it does in CL P4 species
What are the 4 functions of progesterone in sustaining pregnancy?
development of placenta, myometrial quiescence (no uterine contractions), closure of cervix, immunosuppress uterus (to prevent immune attack on fetus)
The _______ triggers parturition.
How does fetus trigger parturition?
fetus gets too big for placenta--> insufficient oxygen--> stress--> cortisol from fetus--> cortisol triggers parturition
Increased cortisol has what actions just prior to parturition?
fetus: maturation of lungs, kidneys, brain; dam: removes progesterone block in placnta (drop in P4)--> increased enzymes--> P4 converted to estradiol--> uterus activated to produce prostaglandin F2α--> parturition; also increases repro tract secretions to wash out cervical seal
In the dam, increased cortisol from fetus triggers increased _______ and increased _________.
estradiol; prostaglandin F2α
What effects does estradiol have before parturition?
increase oxytocin receptors, increase GAP junctions in uterus (synchronous contractions), relax cervix (3)
What effects does prostaglandin F2α have just before parturition? (4)
luteolysis, stimulate relaxin to relax cervix and pelvic ligaments, myometrial contractions
Uterine contractions push the fetus to the cervix, putting pressure on the cervix that causes __________ and release of _________; the fetus enters the birth canal, and the stretch of cervix and vagina causes...
rupture of chorioallantois; allantoic fluid; increase of oxytocin release and stronger contractions (Fergusson's reflex).
What 5 events help with detachment of fetal membranes?
rupture of umbilical cord, shrinkage of chorionic villi, uterine contractions, reduced endometrial blood flow, weight of placenta/gravity