Novel signaling mechanisms in the ovary during oocyte maturation and ovulation

During the peri-ovulatory period, the gonadotropin LH triggers major changes in both the somatic and germ cell compartments of the ovarian follicle. The oocyte completes the meiotic cell cycle to become a fertilizable egg, and dramatic changes in gene expression and secretion take place in the somatic compartment of the follicle in preparation for follicular rupture and oocyte release. The concerted changes are regulated by activation of intracellular signaling pathways as well as paracrine and autocrine regulatory loops. This review will provide a summary of the current knowledge of the molecular events triggered by LH focusing mostly on the signaling pathways required for oocyte maturation.

► cAMP signaling controls MPF and prevents cell cycle reentry in the oocyte.
► cGMP signaling intersects with cAMP signaling to control meiotic arrest.
► The ovulatory LH signal activates multiple signaling pathways in the follicle.
► LH signals are propagated through the ovulatory follicle via release of paracrine factors.