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What happens when a mature ovarian follicle ruptures?

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Diagram of the menstrual cycle showing hormone levels, follicle development, and endometrial changes across 28 days. It highlights menstruation, ovulation, and the follicular and luteal phases, with labeled curves for estrogen, progesterone, FSH, and LH. — menstruation Cyclical changes during a woman's normal ovulatory menstrual cycle.

When a mature ovarian follicle ruptures—a process known as ovulation—the egg, along with surrounding fluid and some torn patches of tissue, is released from the surface of the ovary. These components are directed into the nearby fallopian tube, which serves as the site for potential fertilization and as a passageway to the uterus.123

Following the rupture, the remaining granulosa and theca cells that lined the follicle fill its lumen and undergo a transformation to form the corpus luteum. This structure acts as a temporary hormone-secreting body, producing progesterone and estrogens to prepare the uterine lining for the potential implantation of a fertilized egg.234

If fertilization does not occur, the corpus luteum eventually becomes inactive and degenerates, leading to a drop in hormone levels that triggers the shedding of the uterine lining, known as menstruation.423