So one of the functions of the placenta is to act as an endocrine gland and it basically produces these four different types of hormones. Now the second and probably the primary purpose and the primary function of placenta is to act in gas exchange and nutrient exchange. So the placenta provides nutrients and exchanges gas between the blood of the mother and the blood of the fetus. And this takes place within the corianic villi. So these corianic villi contain the network of blood vessels that are part of the circulatory system of that developing embryo. And notice that the corianic villi are actually surrounded by a semipermeable membrane.