Endocrine, Paracrine, and Autocrine Signaling Pathways That Regulate Ovulation.

The central role of luteinizing hormone (LH) and its receptor (LHCGR) in triggering ovulation has been recognized for decades. Because the LHCGR is present in the mural (outermost) granulosa cell layer of preovulatory follicles (POFs), the LH-initiated signal has to be transmitted to another somatic cell type (cumulus granulosa cells) and the oocyte to release a fertilizable oocyte. Recent studies have shown that activation of the LHCGR initiates vectorial transfer of information among the two somatic cell types and the oocyte and the molecules and signaling pathways involved are now better understood. This review summarizes the newer developments on the complex signaling pathways that regulate ovulation.