B16 melanoma neovessels in the absence of BM contribution. (A) B16 tumors were capable of robust growth even without BM-derived neovascularization (n = 8). (B-C) MECA-32 staining demonstrated the presence of new blood vessels within B16 (B) and LLC tumors (C; scale bars represent 100 μm). (D) By quantifying MVD, it was found that B16 and LLC tumors contained microvessels at similar densities. LLC and B16 tumors are outlined with dashed lines.