Induced chimaerism by transplanting embryonic cells into mouse blastocysts

Embryonic synchronous and asynchronous cells were successfully transplanted into preimplanted mouse blastocysts. At 15–17 days of fetal development, 19% (32/167), 15% (20/130) and 3% (4/117) of the fetuses expressed chimaerism of the ocular pigmentation when transplanted cells were 0, 48, and 96 hours asynchronous respectively. At birth and during postnatal development, 15% (23/153) and 13% (14/111) of the young expressed chimaerism of ocular pigmentation, coat color, and/or functional germ lines when transplanted cells were 0 and 48 hours asynchronous respectively. Five animals from synchronous and two animals from asynchronous cell transplants were chimaeric in functional germ lines but resembled recipient blastocysts in phenotype color. One overtly chimaeric male had progeny with color phenotype of the albino donor cells only. This report provides evidence that transplanted asynchronous as well as synchronous embryonic cells do participate in the final structure of the embryo. In addition, the results of these studies suggest that the micrurgy and transplantation of the cells does not affect substantially subsequent development of the recipient blastocysts.