Mammalian Placentae: Origin and Types | Chordata | Zoology
A mammalian placenta, typically, is a structure produced by the apposition or fusion of the extra-embryonic membranes (i.e., chorion) with the endometrium of uterus for the purpose of physiological exchange. It, therefore, follows that the placenta from the point of view of its origin, consists of two parts- a foetal placenta, furnished by the extra-embryonic membranes and a maternal placenta, [...]