Ex vivo histopathologic analysis of the tumor vascular microenvironment explains the PAT findings. A, H&E staining. Scale bar, 1.5 mm. Necrosis was significantly higher in the Bev-R group compared with Ctrl (Ctrl, ntumors = 14; Bev-NR, ntumors = 13; Bev-R, ntumors = 4). B, CD31-positive MVD (vessel/μm2) was significantly higher for the Bev-R group compared with the Bev-NR group, which itself was lower than Ctrl (Ctrl, ntumors = 14; Bev-NR, ntumors = 13; Bev-R, ntumors = 5). C, ASMA positivity was significantly higher in both the Bev-NR and Bev-R groups compared with Ctrl (Ctrl, ntumors = 14; Bev-NR, ntumors = 14; Bev-R, ntumors = 4). D, Hypoxyprobe, denoting areas of hypoxia-dependent pimonidazole labeling in the tumor tissue, was significantly higher for the Bev-R group compared with the Bev-NR group, which itself was higher than Ctrl (Ctrl, ntumors = 13; Bev-NR, ntumors = 14; Bev-R, ntumors = 5). E, CAIX positivity, which also reflects tissue hypoxia, was significantly increased in the Bev-R group compared with the Bev-NR group (Ctrl, ntumors = 13; Bev-NR, ntumors = 14; Bev-R, ntumors = 5). F, Coverage of CD31-positive vessels by ASMA staining was significantly lower in the Bev-R group compared with Bev-NR and also lower than Ctrl (Ctrl, ntumors = 14; Bev-NR, ntumors = 14; Bev-R, ntumors = 4). G and H, Toluidine blue–positive objects per mm2, reflective of mast cell density in the tumor, were significantly higher in Bev-NR compared with Bev-R and Ctrl groups (Ctrl, ntumors = 12; Bev-NR, ntumors = 12; Bev-R, ntumors = 4; G), though no significant differences in F4/80 staining (H), reflecting macrophages, was observed (Ctrl, ntumors = 14; Bev-NR, ntumors = 14; Bev-R, ntumors = 5). Scale bars, 50 µm. P values are displayed from two-sided Student t tests.