The granulosa cells and theca interna cells hypertrophy, and accumulate lipid droplets. Capillaries and fibroblasts from the theca interna invade the granulosa cells and the result is a unified organized mass of secretory cells, connective tissue, and blood vessels. Lutein cells undergo autolysis with cellular debris removed by macrophages. This starts in intrauterine life, continues unabated through childhood, slows down a bit during the reproductive years of the female, and ends when there are no more primordial follicles in the ovaries. Menopause occurs when the supply of follicles is nearing exhaustion and too few follicles start to develop each month.
Follicles undergo atresia at all stages of development.
Every female starts with approximately 2.5 million follicles per ovary but by birth this number is reduced to app. 1 million per ovary. By puberty this number is down to around 200,000. Remember that only 400 or so are ever ovulated. Corpus luteum has stopped secreting progesterone and estrogens.