Development of a placental blood circulation in rat embryos in vitro.
Rat embryos explanted with their membranes at head-fold stage (9 1/2 days gestation) formed an allantoic placenta which enlarged in culture and developed a foetal blood circulation. Embryos explanted at early somite stages (10 1/2 days) also formed a growing allantoic placenta but only after removal of most of the ectoplacental trophoblast. Assays of total protein in the embryo and placenta suggested that, in the absence of a maternal blood circulation to the placenta, embryo and placenta compete for the respiratory and nutritional resources obtained through the yolk-sac.
D000818:Animals; D004622:Embryo, Mammalian / Q000032:analysis / Q000502:physiology*; D005321:Extraembryonic Membranes / Q000032:analysis; D005865:Gestational Age; D066298:In Vitro Techniques; D010920:Placenta / Q000032:analysis / Q000098:blood supply*; D011506:Proteins / Q000032:analysis; D051381:Rats
D011506:Proteins