Figure 4. Immunohistochemical analysis of proliferating cell nuclear antigen (PCNA) in colonic tissue of F344 rats from groups 1-6. In group 1,we observed PCNA-negative cells (blue color); in group 2, we found PCNA-positive cells (brown color); but experimental groups 3-6 had fewer PCNA-positive cells than the treated controls (group 2). Colonic tissues were examined at 200× magnification.
