Hematopoietic cell generation by SP cells in MethoCult. (A) Relative frequency of colony formation for YS and embryo SP cells 9.5 to 11.5 dpc. Experiments were performed twice in sextuplicate. (B) Giemsa staining of 14-day MethoCult colonies derived from 10.5 dpc YS SP. Most cells displayed morphology and staining consistent with nucleated erythroblast (ne) cells. A smaller percentage of cells displayed morphology and staining pattern consistent with myeloid cells: macrophages (ma), granulopoetic cells (gr). Original magnification, × 400. (C) Fourteen-day MethoCult colonies derived from 10.5 dpc YS SP stained with lineage antibodies Ter119^PE, Gr-1^FITC, and B220^PE.