Distribution of myeloid and erythroid progenitors in GPIIb-IIIa⁺–sorted embryonic bone marrow cells. Embryonic bone marrow cells were sorted with the anti-chicken GPIIb-IIIa MoAb 11C3 or with the anti-human chicken cross-reacting GPIIb-IIIa MoAb AP2. Positively (+) or negatively (−) sorted cells were then cultured in erythroid or myeloid differentiation conditions in semisolid medium. Colonies were MGG stained and scored. (A) Colonies from E14 bone marrow sorted with MoAb 11C3. (B) Colonies from E14 bone marrow sorted with MoAb AP2. (a) Erythroid differentiation medium, (b) myeloid differentiation medium. Mean number of colonies developed from 1,000 cells, in duplicate cultures. Morphology of colonies after MGG staining. (C) Macrophages (M). These colonies were large and dispersed. Bar = 31 μm. (D) Granulocytes (G). Bar = 62 μm. (E) Macrophages/granulocytes (M/G). A tight granulocytic center is surrounded with dispersed macrophages. Bar = 62 μm. (F) Erythrocytes (Ec). Hemoglobinized cells developed in erythroid differentiation medium. Bar = 31 μm.