Figure 2  .

Time course of changes of colonic epithelial architecture after TNBS administration. Representative colonic sections from non-treated iNOS^+/+ (A) or iNOS^−/− (E) mice show normal tissue structure at day 0. (B) and (C) show a notable disruption of the epithelial structure with extensive haemorrhagic necrosis and infiltration of neutrophils in a colonic section from an iNOS^+/+ mouse at two and four days after TNBS administration, respectively. At day 7 (D) oedema was still present in the healing epithelium of a TNBS treated iNOS^+/+ mouse. (F) shows alteration of epithelial architecture with a massive infiltration of inflammatory cells in a colonic section of an iNOS^−/− mouse two days after TNBS administration. At days 4 (G) and 7 (H) inflammatory cells were still present, mainly in the submucosa, while a healing process started in the epithelium. Original magnification × 400.