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Current views on focal defect in colorectal mucosa as a risk factor for development of tumours are presented. It is characterized by such phenotypical changes of the mucosa as cell proliferation activation, changes in ornithine decarboxylase activity and polyamine synthesis, changes in the expression of the blood group antigens and associated carbohydrate antigens as well as the development of small adenomas. All these changes may be biological markers of colonic precancer.

The review deals with the problem of immunohistochemical interactions between parenchymal cells and stromal components of gastric and colonic carcinomas. The authors discuss the individual features of extracellular matrix and mesenchymal cells (fibroblasts, macrophages, lymphocytes, etc.) in the tumours tissue. Own authors' data are used for the analysis.

Qualitative and quantitative changes in secretion of goblet cells of large bowel mucosa in adenomatous polyps (60), adenocarcinoma (30) and bioptates of adjacent transitional mucosa (30) were studied. As neoplasia progressed, mucin profile appeared to follow a certain pattern: it reached its peak in moderate dysplasia in polyps containing predominantly sulphomucins; subsequently both sulphomucin and sialomucin levels decreased. Adenocarcinomas showed a sharp drop in glycoprotein level, and an insignificant build-up of sialomucins was registered in some cases only. Enhanced abnormal secretion was observed in mucinous carcinoma and adenocarcinoma characterized by the presence of large mucinous areas. Also, qualitative changes were identified in transitional mucosa adjacent to tumor.

The method is based on the selective nucleolar staining with silver salts, the number of silver granules serves as an index of the nucleolar organizer activity which corresponds to the number of RNA-polymerases acting in the cell. The number of silver granules is 5.7, 6.3 and 6.8 per cell in mild, moderate and severe dysplasia, respectively. The histogram of the cell distribution, with regard to the silver grain number, in severe dysplasia is characterized by a shift to the left, and by one high peak. The average number of silver grains is significantly increased in non-invasive and invasive carcinoma and reaches the values of 18.8 and 20.4. A histogram in carcinoma is pulled to the right due to the cells with high content of silver grains and has many low peaks this reflecting variability of cells as to the silver grain content.