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-vit ro fertilization programme were performed. Both the oocytes and the em bryos 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 ded uced from the higher incidence of unfertilized eggs arrested at the ge rminal vesicle or metaphase I stage, as well as metaphase II oocytes w ith multiple metaphase plates. Nine triploid and four tetraploid embry os 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 c leaving diploid embryos which exhibited a high degree of fragmentation . No more than 40% of the blastomeres contained a single nucleus. More over, in only one of the 21 diploid embryos could all the blastomeres be considered normal.