The corpus luteum (CL) is a dynamic endocrine gland located within the ovary that regulates the menstrual cycle and the early stages of pregnancy. During ovulation, cells from the ovarian follicle wall form the CL. The hormone progesterone is produced by the corpus luteum, which makes the uterus a healthy environment for a developing foetus. Each time women ovulate a new corpus luteum forms, which then breaks down after they no longer need it to manufacture progesterone.