A mature corpus luteum produces high levels of progesterone; it’s a glandular structure which is formed briefly by enlarged follicular cells at ovulation. When the corpus luteum ceases to function, the concentrations of estrogen and progesterone (hormones) decline rapidly, and in response, blood vessels in the endometrium (uterine lining) become constricted and soon disintegrate and slough away. At Continue Scrolling To Read More Below...