Segmental variations in the surface architecture of the normal rat colonic mucosa.

A microdissection technique used previously in the small intestine has been adapted for the rat colon in order to determine morphometric data and to calculate surface parameters in various proximal and distal segments (caecum, ascending and descending colon, rectum) of normal colonic mucosa. From the caecum to the rectum there was a gradual significant decrease in the diameter of the middle portions of the crypts, in the number of crypts per unit area and the inner intestinal circumference, as well as in the total mucosal surface per mm intestinal length and the surface of all crypts per unit area. However, there was an increase in the surface of the lining epithelium between the crypts from the caecum to the rectum. These findings are of importance when interpreting alterations in colonic function in terms of segmental changes in the mucosal architecture.