What happens to the corpus luteum when fertilization does not occur?

When fertilization does not occur, the corpus luteum undergoes a process of degeneration. The corpus luteum is a temporary endocrine structure that forms in the ovary after ovulation when the follicle that released an egg transforms into this structure. It primarily secretes hormones, particularly progesterone, which helps in preparing the uterine lining for a potential pregnancy.

If fertilization does not take place, the corpus luteum has no reason to continue its hormonal support, leading to its regression. This degeneration occurs approximately 10 to 14 days after ovulation if no pregnancy has been established. As the corpus luteum degenerates, progesterone levels drop, resulting in the shedding of the uterine lining, which is essentially the menstrual phase of the menstrual cycle.

The other options do not accurately describe the fate of the corpus luteum after fertilization is absent. It does not continue to secrete hormones, as this process ceases with its degeneration. Similarly, it does not form a new egg or increase estrogen production, since these functions are tied to the life cycle and hormonal regulation of ovarian follicles and the phases of the menstrual cycle.