Ultrastructure of human oocytes of different maturity stages and the alteration during in vitro maturation

Objective To observe the ultrastructure of human oocytes at different maturity stages and morphologies before and after in vitro maturation. Design Case report. Setting University-based center for human reproduction. Patient(s) A 28-year-old patient with polycystic ovary syndrome undergoing IVM/IVF-ET treatment. Intervention(s) Human chorionic gonadotropin was given to the patient 36 hours before her oocytes were retrieved by transvaginal aspiration. Main Outcome Measure(s) Ultrastructure of human oocytes matured in vitro. Result(s) Obvious ultrastructural differences were found in oocytes at different maturity stages between those cultured in vitro and those matured in vivo. Degenerate structures were observed in abnormal oocytes. Granulosa cell apoptosis rates from abnormal oocytes were higher than those from normal oocytes. Cumulus cells surrounding morphologically abnormal oocytes had a significantly higher frequency of cell apoptosis, as compared with morphologically normal oocytes. Conclusion(s) Obvious ultrastructural differences were found between the oocytes matured in vitro and in vivo.