So the placenta has several important functions. So let's begin with the endocrine function of the placenta. So as soon as implantation takes place the cells of the trophy blast that eventually become the placenta begin to release a hormone known as the human corianic gonadotropin hormone. So HCG and what the human corianic gonadotropin does is it goes on to the corpus luteum found in the ovaries and it causes the corpus luteum to continue to release progesterone and estrogen because these two hormones are needed to actually maintain the thickening of that endometrium. Now eventually, when the placenta actually forms, that placenta will stop releasing human coryonic natural and it will begin to release its own estrogen and its own supply of progesterone and that will ultimately allow the maintenance of that endometrium. So these are the three hormones released by the placenta.