Question: what happens when the corpus luteum atrophies and levels of estrogen/progesterone fall dramatically?
Answer: The hormones produced by the corpus luteum suppress production of the FSH and LH, which leads to its atrophy. The death of the corpus luteum results in falling levels of progesterone and estrogen, which triggers the end of the luteal phase. Increased levels of FSH start recruiting follicles for the next cycle.