Effect of SDF-1 on formation of tubulelike structures by GFP⁺/c-kit⁺ cells in MT plug assay. (A-C) Trichrome-Masson staining of MT plugs containing GFP⁺/c-kit⁺ cells (A) and GFP⁺/c-kit⁺ cells and 100 ng/mL SDF-1 (B-C). Comparing panel A with panels B-C, it is evident that in SDF-1/c-kit⁺ cells containing MT the formation of bigger tubulelike structures, which were interconnected by a higher number of branching points, occurred. (D-I) Immunohistochemistry for VWF (D,G), GFP (E,H), and Hoechst staining (F,I) in transverse section of MT plugs containing c-kit⁺ cells obtained from BM of GFP transgenic mice alone (D-F) or in the presence of 100 ng/mL SDF-1 (G-I). Note that in the presence of stem cells only, sparse and smaller structures were formed (arrows in D-F), while addition of the chemokine induced the formation of more organized cordlike structures that stained positive and negative for GFP (arrows and arrowheads, respectively, in G-I).