Figure 1.

The classical and revised models of hematopoietic hierarchy. (A) The classical model of hematopoietic hierarchy, showing that HSCs as a homogeneous population undergo differentiation in a step-by-step manner following the sequence of MPPs, common myeloid/lymphoid progenitors (CMPs/CLPs), lineage-restricted progenitors (GMPs, MEPs, etc.) and mature cells. (B) The revised model of hematopoietic hierarchy, showing that HSCs as a heterogeneous population are classified into MK/myeloid-biased, balanced, and lymphoid-biased HSCs on the basis of lineage output.