Chromosome analysis in polyploid human embryos.

Cytogenetic investigations have been performed on 436 unfertilized or polyploid human oocytes after in-vitro fertilization at the Department of Obstetrics and Gynaecology, University of Kiel. Thirty-two oocytes had more than two pronuclei 16-20 h after fertilization and were therefore potentially the precursors of polyploid embryos. The total number of fertilized oocytes was 667, and the frequency of tripronucleate ova was 4.8%. These tripronucleate eggs may develop normally up to birth but never lead to viable newborn children. Some of the resulting embryos displayed chromosomal mosaicism, where polyploid karyotypes and normal diploid cells occurred together. It is assumed that the survival rate of polyploid embryos depends upon the percentage of normal diploid cells.