The results of Gpi-1 analysis of the peripheral blood of recipient newborn animals 4 months posttransplant. These animals received transplants of 1 embryo equivalent of day-10.0 PC C57BL/6J yolk sac cells. Recipient animal (B6Hbbd, Gpi-1a) cells express the Gpi-1^a isoenzyme and donor animal (C57B6j) cells express the Gpi-1^b isoenzyme. Donor-type Gpi-1^b enzyme was observed in peripheral red blood cells in these six representative animals and in all 16 animals tested.