Pla*cen"ta (?), n.; pl. L. PlacentÊ (#), E. Placentas (#). [L., a cake,
Gr. &?; a flat cake, from &?; flat, fr. &?;, &?;, anything flat and
broad.] 1. (Anat.) The vascular appendage which connects the fetus with
the parent, and is cast off in parturition with the afterbirth.
In most mammals the placenta is principally developed from the
allantois and chorion, and tufts of vascular villi on its surface
penetrate the blood vessels of the parental uterus, and thus establish
a nutritive and excretory connection between the blood of the fetus and
that of the parent, though the blood itself does not flow from one to
the other.
2. (Bot.) The part of a pistil or fruit to which the ovules or seeds
are attached.
Pla*cen"tal (?), a. 1. Of or pertaining to the placenta; having, or
characterized by having, a placenta; as, a placental mammal.