title: Fetal and placental growth in young, primiparous and old, multiparous rats.
abstract: Fetal and placental weights and peripheral blood progestagen concentrations were examined on days 13, 16 and 22 of gestation in young (3-5 month) nulliparous and old (9-12 month) multiparous, albino Wistar rats. There was no difference in fetal weights at any stage examined whereas placental weights were significantly heavier in the old rats at days 16 (71%) and 22 (38%). Blood progesterone concentrations were similar in the two groups at days 16 and 22 although concentrations of the less biologically active progestagen, 20 alpha-dihydroprogesterone, were higher (61%) at day 16 in the old rats. The relative hypertrophy of the placentas in the old rats could not be explained by reduced litter size or progesterone concentrations: it may represent a compensatory effect in response to a less favorable uterine environment.
authors: Department of Anatomy and Human Biology, University of Western Australia, Nedlands.
authors: A
authors: A
authors: Rahima
authors: N W
authors: NW
authors: Bruce
mesh_terms: D004092:20-alpha-Dihydroprogesterone / Q000097:blood; D000375:Aging / Q000502:physiology*; D000818:Animals; D005314:Embryonic and Fetal Development; D005260:Female; D009929:Organ Size; D010298:Parity; D010920:Placenta / Q000502:physiology*; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D004092:20-alpha-Dihydroprogesterone; D011374:Progesterone