Histopathology

Colonic sections from mice were collected and fixed in 10% neutral buffered formalin for 24 hours at room temperature. Formalin-fixed intestinal tissue was embedded in paraffin, and 4-μm cross sections were mounted on glass slides and stained with hematoxylin and eosin. Histological sections were evaluated by a veterinary pathologist (T.N.) and scored according to the following criteria: (i) distribution of the inflammation: 0, none; 1, focal; 2, multifocal; 3, diffuse; (ii) degree of inflammation: 0, none; 1, mild; 2, moderate; 3, severe; and (iii) extent of erosion and/or ulceration: 0, none; 1, superficial (lamina propria only); 2, moderate (extends to the submucosa); 3, severe (transmural). The cumulative score represents the sum of these three independent criteria.