Fig. 1

Features of colon mucosa by naked eye examination in (1A) control, (2A) S-AOM and (3A) L-AOM groups. Stained colonic mucosa with 0.2 % methylene blue from (1B) control, (2B & 2C) S-AOM and (3B & 3C) L-AOM groups to identify ACF and micro-tumours on the mucosal surface by dissecting microscope (×20 magnification). Colonic tissue sections from (1C) control, (2D & 2E) short and (3D & 3E) long groups to characterise the microscopic features at × 100 magnification following H&E stain. MDF were characterised at × 200 magnification and following staining with 1 % Alcian blue and Neutral red stains in (1D & 1E) normal, (2F & 2G) S-AOM and (3F & 3G) L-AOM in cross-sectional and topographic views, respectively. (Black arrow = tumour observed by naked eye; red arrow = regional lymph node enlargement; red arrow head = flat ACF; yellow arrow head = micro-tumour detected by dissecting microscope; black star = large ACF [>4 crypts/focus] with hyperplasia; red star = large ACF with dysplastic features and green star = MDF)