An ultrastructural application of silver methenamine to the study of mucin changes in the colonic mucosa adjacent to and remote from carcinoma.

A periodic acid-chromic acid-silver methenamine techniqe for visualizing glycoproteins at the electron microscope level was applied to colonic mucosa taken from areas adjacent to and remote from carcinoma. Normal control mucosa was obtained by biopsy of patients with no known gastrointestinal disease. Non-oxidized control sections were run in parallel. Quantitative and qualitative differences in glycoproteins were detected in the mucosa adjacent to carcinoma ('transitional' mucosa, as we call it) as compared with the normal. Furthermore, the vesicles in both the 'intermediate' and absorptive cells elaborate a glycoprotein product and it seems that a direct relationship exists between the increased vesiculation and the markedly developed 'fuzzy coat' in the 'transitional' mucosa. It is suggested that these findings may represent one of the features of an early stage of carcinogenesis. Histochemical and ultrastructural techniques of the kind used in this study may thus be of value in identifying or predicting malignancy in the colonic epithelium.