Participation of the paternal genome is not required before the eight-cell stage for full-term development of mouse embryos.

Differential expression of the paternal and maternal genomes during mouse embryonic development is considered a reason for both genomes being required for development to term. Extending previous studies performed on two-cell embryos, we show here that diploid embryos reconstituted at the four-cell stage from uniparental haploid blastomeres can produce living offspring. This result shows that for normal development to occur, a paternal genome does not need to be associated with a maternal genome within the same nucleus before the eight-cell stage.