In the present study, we demonstrated that DSS‐induced ulcerative colitis causes significant morphologic changes in the colonic wall, including changes in the thickness of the muscular, submucosal and mucosal layers, as well as changes in the depth and width of the intestinal crypts, collagen accumulation, morphological changes in the ganglia of the myenteric plexus, and changes in the distribution of mast cells and intraepithelial lymphocytes (IELs), as well as a marked reduction in MUC‐2 expression in goblet cells. The gene discussed is MUC2; the disease is ulcerative colitis.