preplacental

Main Entry: pla·cen·ta
Pronunciation: pl&-'sent-&
Function: noun
Inflected Form: plural pla·centas or pla·cen·tae /-'sent-(")E/
: the vascular organ in mammals except monotremes and marsupials that unites the fetus to the maternal uterus and mediates itsmetabolic exchanges through a more or less intimate association of uterine mucosal with chorionic and usually allantoic tissues permitting exchange of material by diffusion between the maternal andfetal vascular systems but without direct contact between maternal and fetal blood and typically involving the interlocking of fingerlike vascular chorionic villi with corresponding modified areas ofthe uterine mucosa —see ABRUPTIO PLACENTAE

placenta pla·cen·ta (plə-sěn'tə)
n. pl pla·cen·tas or pla·cen·tae (-tē)
The membranous vascular organ in female mammals that permits metabolic interchange between fetus and mother. It develops during pregnancy from the chorion of the embryo and the decidua basalis of the maternal uterus and permits the absorption of oxygen and nutritive materials into the fetal blood and the release of carbon dioxide and nitrogenous waste from it, without the direct mixing of maternal and fetal blood. It is expelled following birth.

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pla·cen'tal adj.

placenta   (plə-sěn'tə)  Pronunciation Key  The sac-shaped organ that attaches the embryo or fetus to the uterus during pregnancy in most mammals. Blood flows between mother and fetus through the placenta, supplying oxygen and nutrients to the fetus and carrying away fetal waste products. The placenta is expelled after birth. The part of the ovary of a flowering plant to which the ovules are attached. In a green pepper, for example, the whitish tissue to which the seeds are attached is the placenta.