Stage-specific resistance of the HIF-1 neovasculature to VEGFR1 and VEGFR2 immuno-blockade. (A) Inhibition of the development (days 0-14) versus resistance of the maintenance stage (days 14-28) to VEGFR2 (DC101) immuno-blockade as determined by lectin whole-mount and L-PAM analysis. Both L-PAM and FITC-L esculentum–perfused whole mounts demonstrate the marked sensitivity of perifollicular neocapillaries, whereas microvessels farthest from HIF-1 production are resistant to DC101. L-PAM also detected arteriolar and venular dilatation resistant to DC101 treatment in both stages. (B) Quantification of diminution of microvessel density by cross-sectional MECA32-VWF immunofluorescence (white bars; immunofluorescence data not shown) or volume reduction delineated by image extraction L-PAM analysis during day 0 to day 14 (top) or day 14 to day 28 (bottom) VEGFR2 blockade (blue and yellow bars). (C) Western blot analysis of vascular endothelial-cadherin (VE-Cad), VEGR2^Y1173, and total VEGFR2 in mice treated with VEGFR1/2 blocking antibodies. Bars represent 200 μm.