The corpus luteum (Latin for "yellow body") (plural corpora lutea) is a temporary endocrine structure in female mammals that is involved in the production of relatively high levels of progesterone and moderate levels of estradiol and inhibin A. It is colored as a result of concentrating carotenoids from the diet and secretes a moderate amount of estrogen to inhibit further release of Gonadotropin-releasing hormone (GnRH) and thus secretion of Luteinizing hormone (LH) and Follicle-stimulating hormone (FSH).
The corpus luteum develops from an ovarian follicle during the luteal phase of the menstrual cycle or estrous cycle, following the release of a secondary oocyte from the follicle during ovulation. The follicle first forms a corpus hemorrhagicum before it becomes a corpus luteum, but the term refers to the visible collection of blood left after rupture of the follicle that secretes progesterone. While the oocyte (later the zygote if fertilization occurs) traverses the Fallopian tube into the uterus, the corpus luteum remains in the ovary.
The corpus luteum is typically very large relative to the size of the ovary; in humans, the size of the structure ranges from under 2 cm to 5 cm in diameter.