<P> Pre-implantation genetic diagnosis (PGD or PIGD) is a technique used to identify genetically normal embryos and is useful for couples who have a family history of genetic disorders . This is an option for people choosing to procreate through IVF . PGD is considered difficult due to it being both time consuming and having success rates only comparable to routine IVF . </P> <P> Karyotyping involves performing an amniocentesis in order to study the cells of an unborn fetus during metophase 1 . Light microscopy can be used to visually determine if aneuploidy is an issue . </P> <P> Polar body diagnosis (PBD) can be use to detect maternally derived chromosomal aneuploidies as well as translocations in oocytes . The advantage of PBD over PGD is that it can be accomplished in a short amount of time . This is accomplished through zona drilling or laser drilling . </P> <P> Blastomere biopsy is a technique in which blastomeres are removed from the zona pellucida . It is commonly used to detect aneuploidy . Genetic analysis is conducted once the procedure is complete . Additional studies are needed to assess the risk associated with the procedure . </P>

4. in what stages of meiosis do you think nondisjunction is most likely to occur