Figure 7  .

Immunohistochemistry for nitrotyrosine. In colonic sections from non-treated mice (day 0) no staining for nitrotyrosine was found in iNOS^+/+ (A) and iNOS^−/− mice (E). At days 2 (B) and 4 (C) after TNBS administration a diffuse dark staining was localised in infiltrated inflammatory cells and in the necrotic epithelium of an iNOS^+/+mouse. At day 7 (D) nitrotyrosine staining was still present in the apical epithelium in the area of healing mucosa of an iNOS^+/+mouse. Nitrotyrosine staining was absent at days 2 (F), 4 (G), and 7 (H) after TNBS administration in the mucosa of an iNOS^−/− mouse. Original magnification × 400.