Development and progression of experimental colitis.

<p>Male, 6 month-old C57BL/6 mice (<i>n</i> = 20) were exposed to 2% DSS in drinking water for up to 5 days. Mice were sacrificed at Day 0, 3, 7, and 14 of the experimental period (<i>n</i> = 5 per time point). (A) Daily body weight of mice sacrificed at Day 14; mice sacrificed at earlier time points followed a similar pattern. <i>*P</i><0.05 compared to initial body weight on Day 0. (B) Disease Activity Index (DAI) was calculated at the time of sacrifice based on weight loss, stool blood, and stool consistency. (C) Colons were excised and measured lengthwise. (D) H&E stained sections were graded for Histologic Severity Score. (E) Representative images of colon histology on Day 0, 3, 7, and 14 (original magnification × 100; arrowhead = mononuclear infiltrates, thick arrow = mucosal ulceration, thin arrow = epithelial hyperplasia). Data represent mean ± SD, <i>***P</i><0.001, <i>*P</i><0.05 vs. Day 0.