EBs can be induced to form hematopoietic progenitors. Morphology of differentiated hES-derived hematopoietic CFU subtypes detected under all extrinsic treatments, including (A) macrophage, (B) granulocyte, and (C) erythroid colonies, and (D) multipotent colonies containing granulocyte, erythroid, macrophage, and megakaryocyte elements (CFU-GEMM). Scale bars, 100 μm. (E) Wright Giemsa cytospin preparation of cells from a granulocyte colony showing mature neutrophils, basophils (left inset) and eosinophils (right inset). Scale bar, 25 μm. (F-G) Flow cytometry of a representative granulocyte colony, showing staining with CD45 and glycophorin A (F) or CD33 and CD13 (G). (H) Wright Giemsa cytospin preparation of an erythroid colony showing immature erythrocytes and mature enucleated erythrocytes (arrow). Scale bar, 25 μm. (I-J) Flow cytometry of a representative erythroid colony, showing staining with CD45 and glycophorin A (I) or CD33 and CD13 (J); insets in panels F, G, I, and J indicate colonies stained with isotype controls. (K) Hematopoietic progenitor capacity of undifferentiated hESCs and hESCs differentiated as EBs under various treatments for 14 days, detected by placing 1 × 10⁵ cells into CFU assays (n = 4-12, ^*P < .001 compared to control; error bars indicate SEMs). Wells were examined for colony formation after 10-14 days for Ebs. (L) Distribution of colony subtypes derived under each hematopoietic progenitor induction treatment shown in panel K (P ≤ .001).