The Vascular Wall as a Source of Stem Cells

A bstract : We have characterized the emerging hematopoietic system in the human embryo and fetus. Two embryonic organs, the yolk sac and aorta, support the primary emergence of hematopoietic stem cells (HSCs), but only the latter contributes lymphomyeloid stem cells for definitive, adult‐type hematopoiesis. A common feature of intra‐ and extraembryonic hematopoiesis is that in both locations hematopoietic cells emerge in close vicinity to...