Ca2+ 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. Mol. Reprod. Dev. 78:744–756, 2011. © 2011 Wiley Periodicals, Inc.