Production and reproductive performance of hexaparental and octaparental mice

The production of hexaparental and octaparental mice following embryo aggregation is reported. These mice were progeny-tested to determine which cell components were contributing to gamete formation. One chimera (No. 15) was shown to be producing eggs from all three cell strains--white, yellow, and black. The other chimeras tested were not forming germ cells from all of the cell strains involved. The use of these animals for obtaining a minimum estimate of the number of cells giving rise to the embryo proper is discussed. The suggestion is made that multi-embryo aggregates may actually be developmentally different from normal sized embryos and this may result in modified mechanisms of cell recruitment.