Define the term corpus luteum and explain lits function. What does the corpus luteum turn into if there is not implantation of a zygote? Describe the 3 stages of the ovarian cycle and its average length. Describe the 3 stages of the uterine cycle. Identify the stages of the uterine cycle that correlate (time wise) with the stages of the ovarian cycle. What hormones stimulate the proliferative and secretory phases of the uterine cycle?