[Role of oocyte cytoplasmic factors in human IVF failure]

Premature chromosome condensation (PCC) of the sperm chromatin and abnormal dispersion of oocyte chromosomes are independent indirect indicators for cytoplasmic immaturity and cytoskeletal anomalies in the oocyte affecting the normal zygote and embryo formation in human IVF-ET practice. In a group of 66 human unfertilized oocytes, two types of cytoplasmic factors were registered: PCC in 49 (74.24%) and cytoskeletal anomalies in 17 oocytes (25.76%). These data were analyzed according to the main stimulation regimen and female age as well as to the familial factor of infertility. Our results displayed a higher proportion of PCC if the stimulation regimen included gonadotrophins alone (77.55%) compared with the combined GnRH agonist and gonadotrophins administration (22.45%) and in the female age group of 36-40 years (63.33%). Cytoskeletal defects were predominant in the female age group of 31-35 years (46.06%). Remarkable was the significance of cytoplasmic factors in cases of unknown infertility factor--oocytes from these patients included 34.69% of all cells with PCC and 52.94% of all cells with cytoskeletal defects. Hence, these anomalies were probable causes for IVF failure in cases of unexplained infertility Conclusions: 1. The main regimen for hormonal stimulation and the female age influence the cytological status of studied oocytes (cytoplasmic immaturity causing PCC and polyspermy). 2. Cytoplasmic factors (immaturity and cytoskeletal anomalies) are a prognostic factor for the IVF success in cases of unknown infertility problem in the family.