Corpus Luteum

After an egg has matured and been ovulated from the follicle, the empty follicle becomes a corpus luteum. The corpus luteum secretes the hormones estrogen and progesterone, preparing the body for the possibility of conception.

If conception does not take place, the corpus luteum diminishes, leading to a drop in the hormones progesterone and estrogen. This drop in hormones leads to menstruation.