Ca(2+) signaling during maturation of cumulus-oocyte complex in mammals

Under the influence of gonadotropins or growth factors, a close cooperation develops between cumulus cells and the oocyte that is implicated in transmitting signals involved in maintaining or releasing the meiotic arrest in the oocyte. While cyclic adenosine 5-monophosphate (cAMP) is a key molecule in maintaining the meiotic arrest, calcium (Ca2+) may play a role in controlling either spontaneous or gonadotropin-induced oocyte maturation, possibly by modulating intracytoplasmic cAMP concentrations via Ca2+-sensitive adenylate cyclases. This review focuses on the mechanisms related to the origin of the Ca2+ wave that travels from the cumulus cells to the oocyte, and discusses the source of variations affecting the dynamics of this wave.