Abstract
A high rate of normal postimplantation development was achieved when the pronuclei of embryos from matings of DDK females with (CBA .times. C57BL/6J) F1 males were transplanted into enucleated embryos of non-DDK origin. This shows that the DDK egg cytoplasm, not the maternal pronucleus, is involved in the late preimplanation-lethal incompatibility.