placenta

the organ attaching the EMBRYO to the UTERUS . It is a temporary feature, comprising maternal and embryonic tissues, and it allows oxygen and nutrients to pass from the mother's BLOOD to that of the embryo. There is, however, no direct contact of blood supplies. The embryo also receives salt, glucose, AMINO ACIDS , some PEPTIDES and ANTIBODIES , fats and VITAMINS . Waste molecules from the embryo are removed by diffusion into the maternal circulation. It also stores GLYCOGEN for conversion to glucose, if required, and secretes HORMONES to regulate the PREGNANCY . It is expelled after birth.