A hemoglobin-stained cellulose acetate electrophoresis gel loaded with peripheral blood from a control B6.W/W^v (w/wv) and a donor C57BL/6J (C57B6j) animal are depicted. B6.W/W^v are heterozygous for the hemoglobin alleles expressing both hemoglobin single (Hbb^s) and hemoglobin diffuse (Hbb^d), whereas the donor C57BL/6J animals are homozygous for hemoglobin single (Hbbs/Hbbs). Five representative B6.W/W^v recipient animals receiving transplants of 10 embryo equivalent doses (1.4 × 10⁶ cells) of day-10 PC C57BL/6J yolk sac cells were also bled and the hemoglobin bands were stained are indicated in lanes 1 through 5. Because the intensity of the Hbb^s band did not increase in proportion to that of the Hbb^d bands in these five recipients, there was no evidence of engraftment.