Autosomal Trisomy and Triploidy Are Corrected During Female Meiosis in .

Trisomy and triploidy, defined as the presence of a third copy of one or all chromosomes, respectively, are deleterious in many species including humans. Previous studies have demonstrated that with a third copy of the X chromosome are viable and fertile. However, the extra X chromosome was shown to preferentially segregate into the first polar body during oocyte meiosis to produce a higher frequency of euploid offspring than would be generated by random segregation.