Estrogen and progesterone in the first 2 months pregnancy are produced by:
(A) Fetal ovaries (B) Fetal adrenal (C) Placenta (D) Corpus luteum
(D) Ans: D. Corpus luteum(Ref Williams 24/e p169; Ganong 25/e p412, 24/e p414).Estrogen and progesterone in first 2 months of pregnancy - Produced by Corpus luteum.Functions of corpus luteum:Enlarged corpus luteum of pregnancy secretes estrogens, progesterone & relaxin.Progesterone & relaxin -Helps maintain pregnancy.By inhibiting myometrial contractions.Progesterone prevents prostaglandin production by uterus - Stops contractions.Corpus luteum function begins to decline after 8 weeks of pregnancy.Yet persists throughout pregnancy.In humans placenta produces sufficient estrogen & progesterone from maternal & fetal precursor taking over corpus luteum function after 6th week of pregnancy.Ovariectomy before 6th week a Hence cause aboion.Ovariectomy after 6th week doesn't affect pregnancy.Note:hCG secretion decreases after initial marked rise.Estrogen & progesterone secretion increase until just before paurition.