[Contribution of first polar body analysis to understanding of human aneuploidy mechanism].

In our species, reproduction failure rate is high. Clinical evidence is miscarriage where chromosomal origin was largely involved (66% of cases). The development of assisted reproduction techniques made possible to analyse unfertilized oocytes and preimplantation embryos. The results have shown a high rate of chromosome abnormalities before implantation (50%). Two mechanisms were identified which could generate aneuploidy, the meiosis non-disjunction and the premature separation of sister chromatids (PSSC). A FISH analysis of the first polar body, a cell complementary to the oocyte after meiosis, can be performed before intracytoplasmic sperm injection. We studied 2 distinct populations (patients over 38 years old and patients with recurrent implantation failure) and we confirmed that PSSC is the major mechanism linked to advanced maternal age in human.