This review summarizes our knowledge on ovulation process. After gonadotropin surge or LH injection, 13 factors are involved in the follicular rupture. All of them plays a role since the inhibition of their synthesis or activity prevents the rupture of preovulatory follicles or reduces the number of ovulations. Most of them are involved in all inflammatory reactions. At the apex of the follicle, blood vessels constriction, free TNF alpha and probably factors from the ovarian epithelium cells are involved in the full dissociation of follicle layers and cell death, allowing the localized rupture of the follicle wall. Gonadotrophins and angiotensine II are the only factors able to induce both follicle rupture and meiotic resumption.