Now progesterone is initially released by the corpus luteum. So after ovulation takes place and the ovum is released into our parrot meal cavity, the corpus luteum eventually forms and that corpus luteum begins to release our progesterone hormone. Now, once our corpus luteum actually degenerates during the process of pregnancy, our placenta, the structure that basically supplies the growing fetus with nutrients, begins to release our progesterone. So we have two structures that are capable of releasing progesterone. Initially it's the corpus luteum, but eventually when the corpus luteum degenerates during the process of pregnancy, it's the placentha that releases our progesterone. Now, what exactly is the function of progesterone?