The placenta (from Greek plakuos, flat cake) is an organ created from the zygote that links two individuals, the mother and the fetus. Throughout the pregnancy, placental mass maintains a dynamic relationship with the weight of developing fetus. The placenta serves to attach the embryo-fetus to the uterine wall and to exchange nutrients, wastes, and gases between the maternal blood and the embryo-fetal blood. It also provides endocrine and immune support for the developing fetus.

The placenta forms by the differentiation of the trophoblast (the outer cell mass of the early embryo that gives rise to the placenta) in two different layers, the cytotrophoblast (mitotically active) and the syncytiotrophoblast (lacunas forming tissue able to fuse the placenta to the wall of the uterus). The placental anatomy is comprised of the placental parenchyma, umbilical cord, and amnion...