Morphological and cytogenetic observations of unfertilized human oocytes and abnormal embryos obtained after ovarian stimulation with pure follicle stimulating hormone following pituitary desensitization.

Morphological and cytological observations of 189 unfertilized oocytes and 40 abnormal embryos obtained from 32 patients in a routine in-vitro fertilization programme were performed. Both the oocytes and the embryos were mounted whole to preserve the original topology of all the structural elements. With the applied protocol of ovarian stimulation associating pituitary desensitization and follicle stimulating hormone stimulation, a high degree of immaturity of the unfertilized eggs was observed in comparison with previous reports. This immaturity was deduced from the higher incidence of unfertilized eggs arrested at the germinal vesicle or metaphase I stage, as well as metaphase II oocytes with multiple metaphase plates. Nine triploid and four tetraploid embryos were analysed: except for one tetraploid embryo, all the polyploid embryos cleaved. The percentages of mononucleated blastomeres in these polyploid embryos were 57 and 27% respectively. We also analysed 21 cleaving diploid embryos which exhibited a high degree of fragmentation. No more than 40% of the blastomeres contained a single nucleus. Moreover, in only one of the 21 diploid embryos could all the blastomeres be considered normal.