Ped gene expression by embryos cultured in vitro.

The rate of cleavage division of preimplantation mouse embryos has been shown to be influenced by the Ped gene, a gene linked to the H-2 complex, the major histocompatibility complex of the mouse. There are two functional alleles of the Ped gene, slow and fast. To examine Ped gene expression outside of the maternal uterine environment, embryos from inbred and congenic mouse strains were cultured in vitro, in chemically defined medium, for various lengths of time. The results of these studies show that the difference in the rate of cleavage division between slow-developing strains (Ped slow) and fast-developing strains (Ped fast) is maintained in vitro. Thus, the Ped gene phenotype of developing embryos is an intrinsic property of the embryos themselves.