Figure 2.

Relationship between specialized endothelial cell (EC) subpopulations. (A) Schematic diagram of potential EC fates. Type E ECs have the potential to become type H ECs, which in turn can give rise to type L ECs. Type H ECs have the potential to become arterial ECs (AECs), but it remains unclear whether type E ECs can do the same. The ability of type E, H, and L ECs to give rise to venous ECs (VECs) remains to be determined. Solid arrows indicate strong evidence; dashed arrows indicate possible connections. (B) Arrows indicate expansion of GFP⁺ vessels into the marrow cavity: green fluorescent protein (GFP) (Apln-CreER) (green) and endomucin (Emcn) (red). (Overview fluorescent images from Langen et al. 2017; reprinted, with permission, from Nature Publishing Group © 2017.)