The effect of cells transferred into the mouse blastocyst on subsequent development

Bone marrow cells from CBA T6T6 mice and testicular teratocarcinoma cells from 129 SvSl mice were transferred into blastocysts from random-bred Swiss albino mice. The blastocysts were allowed to develop in foster mothers and the adults resulting from these blastocysts were studied for evidence of an effect of the transferred cells. A total of 137 adults resulted from the experiments, and one of the mice that had received teratocarcinoma cells in the blastocyst stage showed several thin stripes of agouti hair. All the adult animals received grafts of skin from animals identical to those supplying the cells. In all cases the animals that resulted from blastocysts into which cells had been transferred maintained skin grafts for a significantly longer period than controls. In a number of cases the graft developed agouti hair and in two cases the graft was maintained for approximately 2 mo. These experiments indicate that the transferred cells were able to establish small colonies in the embryos and that some of these cells persisted into the adult.