secretory phase, the phase of the menstrual cycle after the release of an ovum from a mature ovarian follicle. The corpus luteum, stimulated by luteinizing hormone (LH), develops from the ruptured follicle. It secretes progesterone, which stimulates the development of the glands and arteries of the endometrium, causing it to become thick and spongy. In a negative-feedback response to the increased level of progesterone in the blood, the secretion of LH from the pituitary decreases. In the absence of an embryo and its secretion of chorionic gonadotropin, the secretory phase ends. The corpus luteum involutes, progesterone levels fall, and menstruation occurs. Also called luteal phase, progestational phase. Compare menstrual phase, proliferative phase.
