The aim of the present study was to assess whether the changes in the epithelial glycoproteins seen in the mucosa adjacent to tumors are specific premalignant markers or secondary reactive phenomena. A secondary objective was to assess whether ulcerative colitis and Crohn's Disease could be distinguished from one another histochemically. The carbohydrate prosthetic groups from colonic epithelial glycoproteins were characterized histologically and histochemically from 17 cases of ulcerative colitis, 21 cases of Crohn's Disease and 19 cases of diverticular disease. Two histochemical parameters - the relative proportion of sulpho- and sialomucin and the side-chain substitution pattern of O-acetylated sialic acid - were assessed using a battery of seven histochemical techniques. Serial sections from each specimen were also evaluated morphologically, using hematoxylin and eosin. In addition, the patterns of O-acetylated side-chain sialic acid from the three inflammatory bowel diseases were compared to data previously acquired from the mucosa adjacent to colonic tumors. Results indicate that neither focal changes nor the predominance of sialomucins are specific to the mucosa adjacent to tumors. As well, changes in one histochemical parameter were independent of changes in the other parameter. No histochemical class of epithelial glycoproteins was specific to any of the inflammatory bowel diseases and, therefore, it was not possible to distinguish between ulcerative colitis and Crohn's Disease on the basis of the histochemical techniques used in the present study. It was also noted that the histochemical changes in ulcerative colitis, Crohn's Disease and diverticular specimens were not related to the degree of inflammation. Finally, as a group, Crohn's Disease specimens showed a loss of sulphomucin-sialomucin gradient along the length of the crypts. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate