Structure of Placenta

STRUCTURE OF PLACENTA    

        The concept of the placenta cannot be clarified without a structural study of its complex nature, which is based on its dual origin. Initially two tissues are known as maternal and fetal tissues. the maternal tissues from the decidua basalis  the eroded and the compact layer. The name "decidua" (meaning 'to shed') refers to the pregnant endometrium, with different regions of the decidua assigned different names depending on their relationship to the implantation site. Decidua basalis refers to that part of the endometrium beneath the blastocyst that contributes to the placenta. The thin portion of the endometrium on the lumen side of the uterus that cover the implantation site is the endometrium lining the uterus other than at the implantation site is the decidua parietalis. The foetal tissues from the chorion frondosum (chronic membrane with their villi). The two layers are separated by a space called intervillous space. The space is developed with aggregation of cavities of early chorionic trophoblast. Trophoblast is an ordinary semipermeable membrane that governs the distribution of substances between the mother and foetus. As the embryonic body develops, it separates from the various membranes until only the umbilical cord connects the foetus with the placenta.