Post-fertilization polyploidy in human preimplantation embryos fertilized in-vitro.

The development of in-vitro fertilization (IVF) and embryo transfer (ET) as a treatment for certain forms of infertility has emphasized the need for more information on why so many preimplantation embryos fail to develop beyond the very early cleavage stages. Analysis of nuclei from embryos that had ceased to grow or that were morphologically abnormal was carried out using one of two techniques: measurement of the DNA content of their nuclei, or observation of the number of Y chromosomes per nucleus. It was found that there was a correlation between the length of time in culture and abnormal development of polyploidy in a number of the cells. On the other hand, a small proportion of polyploid cells observed in a morphologically normal expanded blastocyst probably represents the normal precursors of polyploid trophoblast cells as observed in other mammalian species.