Histological assessment of tumor angiogenesis. Representative fluorescence images of tumor sections from mice inoculated with (A) CT26 cells or (B) LLC1 cells, which were stained with anti-CD31 (red) after 28 days to detect tumor-associated blood vessels. The quantitative results were determined by the average blood vessel area per microscopic field in tumor sections from mice inoculated with (C) CT26 cells or (D) LLC1 cells. Values are means + SEM; * p < 0.05; ** p < 0.01, *** p < 0.001 using unpaired t-tests (n = 3). Representative fluorescence images of tumor sections from mice inoculated with (E) CT26 cells or (F) LLC1 cells were stained with anti-VEGF (vascular endothelial growth factor) (red) to detect tumor vascularization. The quantitative results were determined by the average VEGF expression area per microscopic field in tumor sections from mice inoculated with (G) CT26 cells or (H) LLC1 cells. Values are means + SEM; ** p < 0.01, *** p < 0.001 using unpaired t-tests (n = 3). Magnification A,B,E,F: 50 µm.