Figure 2

CD34, α-SMA, CD133, CD90, CD105, CXCR4, VEGFR1, VEGFR2 expression in growth plate and in the surrounding GOR (n = 23). An entire digit section was scanned by TissueFAXS (overview) including uncalcified cartilage (C), area of ongoing calcification (*), joint cavity (JC), surrounding soft tissue (ST), articular cartilage (AC), Groove of Ranvier (GOR), POC, and SOC. Immature endothelial cells in POCs expressed CD34 (A), abluminal coverage with α-SMA⁺ smooth muscle cells was found on vessels in newly formed bone but not in POCs and SOCs (B). Single CD133 precursor cells were found in POCs in close proximity to newly formed vessels (C), mesenchymal progenitor cells expressing CD90 (D) and CD105 (E) co-localized with CD34⁺ endothelial cells in POCs. CXCR4+ cells (F) could be localized in POCs. VEGFR1 (G) is expressed on endothelial cells of vessels in newly formed bone, while VEGFR2 (H) is expressed on immature CD34⁺ endothelial cells in POCs. The groove of Ranvier (GOR) (J) showed intense vascularisation (K) with mesenchymal progenitors expressing CD105 (L). A representative isotype control was included (I). Large arrowheads indicate the area of the insert (scale bar equals 50 μm), small arrowheads indicate specific cells.