RESUMO
BACKGROUND: A case of idiopathic primary infertility was attributed to a block in oocyte meiosis affecting the transition between metaphase I and metaphase II. METHODS AND RESULTS: A couple suffering unexplained primary infertility 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 polar body, and therefore were not injected. The failure of these assisted reproduction cycles was, in both cases, due to the immaturity of the oocytes recovered. Cytogenetic analysis of the oocytes retrieved for ICSI provided evidence of meiotic arrest. Using cytogenetic staging criteria we were able to show that this arrest occurred between metaphase I and anaphase I. CONCLUSIONS: Meiotic blocks affecting oocytes have already been described for various mammals. We discuss here mechanisms that might be involved in this possibly inherited disorder in humans, and ways in which our knowledge of them could be increased.
