Figure 3: Histological findings in the colon, lung, liver, and kidney of the normal and UC rats (hematoxylin and eosin stain, × 100). (a) The colonic mucosa structure in the normal rats was intact. (b) The colonic mucosa and submucosa defects could be clearly seen with infiltrations of inflammatory cells in the lamina propria of after TNBS-ethanol enema (24 hours). (c) Four weeks later, colonic tissue necrosis was obvious, and some necrotic tissues stripped and formed ulcers. The glands of the lamina propria atrophied or even disappeared. (d) The lung tissue had normal alveolar structure and no inflammatory infiltration and exudate. (e) After TNBS-ethanol enema, the lung tissue can be seen massive lymphocytes, even lymphocytic nodules around the bronchi. (f) Four weeks later, blood vessel wall and bronchial wall were obvious proliferation. (g)–(i) Rat liver structure was basically normal ((g): normal group, (h): group, and (i): group). The structure of hepatic cords was clear, liver cells distributed radially around central venous and less fat vacuoles, and the structure of hepatic lobules was intact. (j) The histological appearance of the normal kidney was shown. (k) and (l) Compared with the normal group, glomerular cells and mesangial matrix of the model rats had no significant necrosis and hyperplasia.