Figure 2. HSCs and their niche cells surround sinusoids throughout the bone marrow.

a. Sections through the bone marrow of Scf^gfp/+ mice show that HSC niche cells (green) include mesenchymal stromal cells and endothelial cells that surround sinusoids and potentially other blood vessels throughout the bone marrow⁶⁴. b–d. High magnification shows that Scf-GFP overlaps with the endothelial marker endoglin but also extends beyond the endoglin on the abluminal side of the sinusoids, indicating expression by mesenchymal stromal cells. e. Scf-GFP is not expressed by osteopontin+ bone lining cells around trabecular bone, but is expressed by some nearby perivascular cells. f. Cxcl12-DsRed exhibits a similar expression pattern, primarily by perivascular mesenchymal cells and endothelial cells around sinusoids throughout the bone marrow, in a pattern that strongly overlaps with Scf-GFP in Cxcl12^DsRed/+; Scf^gfp/+ mice¹⁷. g–j, Cells that are CD150+ (g) and CD48 and Lineage marker negative (h) are usually found immediately adjacent to Scf-GFP+ perivascular cells (i) in the bone marrow (see j for merge). Images are from references^17,64.