VEGF-D expression in vivo.

In situ gene transfer to rat cremaster muscle was confirmed by direct visualization of GFP using confocal fluorescence microscopy. Discrete muscle fibers were visualized using phase-contrast (A) and fluorescence (B, C) microscopy 5 days after the injection of Ad-GFP. Immunostaining for VEGF-D revealed maximum expression 5 days (E) and detectable levels 21 days (F) after the injection of Ad-VEGF-DΔNΔC but not of control Ad-GFP (D). Positive staining was observed in muscle fibers, fibroblasts, and blood vessel walls.