PCR analysis to sex embryos

Gel electrophoresis of PCR products. The upper band indicates the presence of a Y-chromosome specific repetitive sequence showing that the DNA comes from a male embryo of embryos. DNA was isolated from single cells from cleavage stage human embryos that had been generated by IVF. In this case male offspring will carry an X-linked disease. The determination of sex therefore allows selective implantaion of female embryos.