Fig. 6. Schematic representation of hematopoietic differentiation in embryos and embryoid bodies. Pluripotent cells (ES cells or cells from the inner cell mass, ICM) undergo mesodermal commitment and differentiation into the common precursor of hematopoietic and endothelial lineages (hemangioblast). We have demonstrated a cell with both primitive erythroid and definitive lymphoid-myeloid potential, properties predicted for the earliest embryonic hematopoietic stem cell: 
-HSC. The -HSC is deficient at repopulation of adult hosts owing to some combination of its transient nature, its homing properties and its response to the adult environment (top panel). BCR/ABL (lower panel) enables repopulation by altering one or more of these deficiencies, allowing both lymphoid and myeloid potential to be observed in engrafted animals.
