Study of the roles of caspase-3 and nuclear factor kappa B in myenteric neurons in a P2X7 receptor knockout mouse model of ulcerative colitis

Figure 14  Photomicrographs of Masson’s trichrome-stained transverse sections of the distal colons of mice in different groups. A1 and A2: Wild-type (WT) sham 24 h; B1 and B2: WT colitis 24 h; C1 and C2: Knockout (KO) sham 24 h; D1 and D2: KO colitis 24 h; E1 and E2: WT sham 4 d; F1 and F2: WT colitis 4 d; G1 and G2: KO sham 4 d; H1 and H2: KO colitis 4 d groups. Collagen fibers (blue) in the lamina propria and submucosal layer, intermingled with and involving the muscle layer, and circumscribing the myenteric ganglia were observed in the sham groups. In the WT colitis group, there was a decrease in the number of these fibers in the submucosal layer, and the collagen fibers in this layer were hyperplastic and disorganized. Moreover, the number of collagen fibers was increased in the lamina propria, and collagen fibers were intermingled in the muscular layer. Tissue was better preserved in the KO colitis group. WT: Wild-type; KO: Knockout; M: Mucosal layer; LP: Lamina propria; MM: Mucosal muscle; SM: Submucosal layer; ML: Muscle layer; CM: Circular musculature; LM: Longitudinal musculature; White arrows: Myenteric ganglion.