Figure 1.

Schematic of stem cell and progenitor cell classification. The hemangioblast is believed to be an embryonic precursor for HSCs and possibly also EPCs. HSCs differentiate into hematopoietic progenitors and then into the various blood cell lineages, but there is also evidence that HSCs can transdifferentiate into non-hematopoietic cells. MSCs are believed to differentiate into multiple mesenchymal lineages. Dotted grey lines indicate points that are still controversial.