Chromosome identification in human oocytes and polar bodies by spectral karyotyping

Sixty unfertilized human oocytes and two fresh polar bodies were karyotyped by spectral karyotyping (SKY). The oocytes were provided by 29 women ranging from 30 to 42 yr of age. The mean hybridization efficiency for oocytes was 95.2% (60/63). Nondisjunction of bivalent chromosomes (13.3%) and predivision of sister chromatids at meiosis I (3.3%) were unequivocally determined by analysis first with SKY and then fluorescence in situ hybridization. Four oocytes (6.7%) were hyperhaploid, six (10.0%) were hypohaploid, one (1.7%) showed balanced predivision, and another (1.7%) was diploid. No specific structural rearrangements were detected. This study demonstrates that the SKY technique can be used successfully as an alternative method of karyotyping second meiotic metaphase chromosomes from human oocytes and polar bodies in appropriate spreads.