Implantation of VEGF-releasing pellets enhances UVB-induced cutaneous angiogenesis in wild-type mice. Mice were subcutaneously implanted with control or VEGF165 slow-releasing pellets, followed by irradiation with a single UVB dose of 5.4 × 10^-2 J/cm² after 5 days. Histologic analyses revealed marked tissue edema in mice that underwent implantation with VEGF-releasing pellets after 2 days (D) but only minor edema in sham-irradiated mice bearing VEGF-releasing pellets (B) and in UVB-irradiated mice bearing control pellets (C). No major changes were seen in sham-irradiated mice bearing control pellets (A). CD31 stains revealed pronounced neovascularization and vessel enlargement in mice bearing VEGF pellets after UVB irradiation (H), whereas less pronounced vascular enlargement was found in sham-irradiated mice with VEGF pellets (F) and in UVB-irradiated mice bearing control pellets (G). No major vascular changes were observed in sham-irradiated mice that underwent implantation with control pellets (E). Nuclei are labeled blue (Hoechst stain). Scale bars, 200 μm. A Plan Fluor 20 × objective with an aperture of 0.50 was used for panels A-H. Morphometric analyses of CD31-stained skin sections confirmed a significant increase in the cutaneous area covered by vessels (I), average vessel size (J), and average vessel density (K) in UVB-irradiated mice that underwent implantation with VEGF-releasing-pellets (▪) compared with UVB-irradiated mice that underwent implantation with control pellets (□). Sham-irradiated mice that underwent implantation with VEGF-releasing pellets showed a significant increase in the average cutaneous area covered by vessels (I) and vessel size (J), but not vessel density (K), compared with mice bearing control pellets. ^***P < .001; ^**P < .01; ^*P < .05. n.s. indicates not significant. Data represent mean values ± SD.