Progesterone is a principle female sex hormone. It is a steroid. It is secreted during the later half of the menstrual cycle in human females by temporary endocrine tissue, the corpus luteum. The luteinizing hormone (LH) of anterior pituitary brings about a rupture of the Graafian folllicle to release the ovum and changes the ruptured follicle into a yellow structure called corpus luteum, which secretes progesterone.