Hypothalamus Gonadotropin Releasing Hormones (GnRH) are released by the hypothalamus. Pituitary GnRH stimulates pituitary to release FSH and LH. Ovary FSH and LH act on ovary. LH stimulates ovulation, formation of corpus luteum from the ruptured follicle and secretion of progesterone by the corpus luteum. Pregnancy Progesterone maintains pregnancy.