Anemia, erythroblastosis, and thrombocytopenia in PDGF-B null mutant embryos.

Peripheral blood hemoglobin concentration (left), platelet counts (center), and erythroblast (nucleated erythrocytes) counts (right) in wild-type^(+/+), heterozygous^(+/−), and PDGF-B mutant^−/− embryos were measured at E17.5 in blood (*P < .001 by the Mann-Whitney test for comparison between wild-type and PDGF-B^−/− mutants or between PDGF-B^+/− and PDGF-B^−/−; ‡P = .01 for comparison between PDGF-B^+/+and PDGF-B^+/−).