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Figure 4 (a) Evens Blue (EB) concentration of rabbit ears 3 to 14 days after adenovirus-encoding angiopoietin-1 gene (Ad.Ang-1) or adenovirus-encoding vascular endothelial growth factor gene (Ad.VEGF). Because EB binds to albumin in vivo, leakage of this protein into the extravascular space is a measure of vascular permeability. Values recorded as EB: ng/mg tissue. Vascular endothelial growth factor induces vascular permeability peaking at seven days; (b) EM Section from Ad.VEGF-injected animals: left shows a small "gap" between endothelial cells (arrow); Right shows increased cytoplasmic vesicles (arrows). These were not found in Ang-1- or control adenovirus without transgene insert (Ad.Null)-treated animals. (c) Photographic images of rabbit ears seven days after injection of Ad.Ang-1 or Ad.VEGF showing bluish discoloration in VEGF-treated animals (top panel), and corresponding laser Doppler imaging (lower panel). Tissue perfusion increased in both; however, the vessel images of the VEGF-injected Ang-1-injected ears differed markedly (see text for details). (d) Bar graph showing mononuclear cell infiltration in the subcutaneous tissue after Ad.Ang-1, Ad.VEGF, or Ad.Null injection. Data are expressed as cells per high-power field (mean ± SD).