Figure 3: vWF-positive endothelium in corpus cavernosum. Representative immunohistochemical staining of vWF-positive endothelium (indicated by arrows) in (a) control, (b) DMED, (c) DMED + Sil, (d) DMED + PK, and (e) DMED + Sil + PK groups. Scale bars = 50 μm. (f) Semi-quantification results of vWF (presented as vWF-positive area/total area ± s.d.) in each group. *P < 0.05; **P < 0.005. DMED: rats with diabetes mellitus-associated erectile dysfunction; Sil: sildenafil; PK: pancreatic kininogenase; vWF: von Willebrand factor; s.d.: standard deviation.