Figure 2.

Representative fluorescence photomicrographs of longitudinal views of whole-mounted rat sciatic nerves (a–c) and their respective paraffin-embedded cross sections (d–f) 4 weeks after treatment. Before sacrifice and harvesting of the nerves, in vivo perfusion with FITC-conjugated BS-1 lectin, an endothelial-specific ligand, was performed. (a and d) Samples taken from a nondiabetic saline-injected control animal, showing a normal pattern of vascularity. (b and e) Samples taken from a diabetic animal 12 weeks after induction of diabetes and 4 weeks after sham treatment (saline injection). The total network of vasa nervorum is markedly reduced, resulting in an irregular distribution pattern and areas of nonvascularized nerve tissue. Note in particular the reduction of stained endoneurial vessels in the cross-sectional image. (c and f) Samples from a rat after 12 weeks of diabetes and 4 weeks after VEGF-1 gene transfer. Vascularity appears well preserved, and the number of visible vessels in the cross section appears similar to that of a normal sciatic nerve. ×2 (a–c); ×4 (d–f).