Manufactured hexaparental mice show that adults are derived from three embyronic cells.

Two female chimeric mice have been produced by aggregates of three genetically marked eight-cell embryos. All three embryonic genotypes are clearly expressed in the pigment pattern of the adults. These hexaparental mice together with their littermates demonstrate that, in the 64-celled blastocyst, at least three cells, and probably only three, are the source of all adult tissues.