An idiopathic infertility with oocytes metaphase I maturation block

BACKGROUND: A case of idiopathic primary infertility was attributed to a bl ock in oocyte meiosis affecting the transition between metaphase I and meta phase II. METHODS AND RESULTS: A couple suffering unexplained primary infer tility was unsuccessfully treated by various means of assisted reproductive technology. After four unsuccessful pregnancy attempts using intrauterine inseminations (IUI), IVF was attempted (all oocytes remained unfertilized), followed by an ICSI cycle. None of the retrieved oocytes expelled the pola r body, and therefore were not injected. The failure of these assisted repr oduction cycles was, in both cases, due to the immaturity of the oocytes re covered. Cytogenetic analysis of the oocytes retrieved for ICSI provided ev idence of meiotic arrest. Using cytogenetic staging criteria we were able t o show that this arrest occurred between metaphase I and anaphase 1. CONCLU SIONS: Meiotic blocks affecting oocytes have already been described for var ious mammals. We discuss here mechanisms that might be involved in this pos sibly inherited disorder in humans, and ways in which our knowledge of them could be increased.