What Makes PGD for Aneuploidy Screening (AS) by Polar Body (PB) Analysis Interesting and Possible?
Since it has been reported that in humans 90% of embryos are aneuploid as a result of malsegregation mechanisms in maternal meiosis I,1 the detection of abnormal oocytes in IVF treatments has become of considerable importance. Figure 1 Schematic representation of female gametogenesis. Figure 1. Schematic representation of female gametogenesis. Taking into account the results obtained from the study of recognized pregnancies,2 and gametes,3,4 the conclusion is that the segregation of chromosomes during meiosis is extremely abnormal in humans, and especially during the first meiotic division of the oocytes. This is in agreement with the fact that the first female meiotic division starts during the prenatal stages (at about 11th week of pregnancy) and is not completed until time of ovulation during the fertile life of the woman, between, approximately, 11 and 40 years later2 (fig. 1). Advances in the procedures of assisted human reproduction have facilitated the development of methods of
