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The chromosome complement of human uncleaved oocytes
1Department of Obstetrics and Gynaecology, Faculty of Medicine and Health Sciences, U.A.E. University, Al Ain, UAE.
Objective:
Investigation of human oocyte chromosomes that fail to fertilize may provide data essential to the assessment of reproductive failure. In view of this, 121 uncleaved human oocytes were analyzed cytogenetically to assess the type and frequency of chromosomal abnormality.
Methods:
Oocyte recovery was done from patients undergoing in vitro fertilization (IVE) procedures. Then, these oocytes were preincubated and inseminated in vitro. Karyotyping was attempted in 121 oocytes lacking signs fertilization 50 h after insemination.
Results:
Sixty-nine oocytes were adequately karyotyped. The overall frequency of chromosomal aberration was 47.6%. Amongst these, 34.8% were aneuploidy, the frequency of which was significantly higher (p < 0.05) in patients > 35 years of age. Diploidy and hyperploidy was noted in 7.2% and 2.8% respectively. Translocation were noted in 2.8% and in 18.8% of human oocytes sperm chromosome condensation appeared prematurely in the G1 phase. No correlation was a found between specific chromosomal aberrations and type of fertility, stimulation treatment or gonadotropin levels.
Conclusion:
The high rate of chromosomal disorders (47.6%) in human oocytes may contribute significantly towards their failure to fertilize in vitro.
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