Cytogenetic analysis of human oocytes from fertile women.

Several reports have shown a relatively high incidence of chromosome anomalies in human inseminated-unfertilized oocytes from infertile women. In the present study, cytogenetic analysis was attempted in 73 human oocytes from 17 fertile women in order to establish the incidence of chromosome anomalies in the fertile population and to compare this with the incidence in inseminated-unfertilized oocytes from infertile women. Of 56 oocytes that could be analysed, 42 oocytes were haploid, 12 were hypohaploid and two exhibited fragmented chromosomes. The low rate of chromosome anomalies (3.6%) found in this population suggests that there is natural selection at fertilization against diploid oocytes and oocytes with fragmented chromosomes. This result also questions the high incidence of chromosome anomalies found in previous reports using inseminated-unfertilized oocytes.