A histochemical study of fibronectin (FN) of the large intestine by the immunoperoxidase technique.

Histochemical studies of fibronectin in cancer and adenoma of the large intestine were conducted by the immunoperoxidase technique. The fibronectin immunohistochemical reaction was present in frozen sections, whereas it was obviously suppressed in the formalin-fixed sections. In the normal mucosa of the large intestine, the reaction was strong in the basement membrane of epithelial cells and weaker around the interstitial cells of the lamina propria mucosa. The reaction in cancer tissues was negative in the basal part of the gland, while the interstitial connective tissue was strongly positive for fibronectin. In adenoma, there was a correlation between the intensity of the fibronectin reaction and the degree of epithelial cell atypism; that is, in a gland with severe atypism the reaction was very weak or absent, while in a gland with mild atypism a weak reaction still persisted. It is concluded that this technique will serve as a useful supplementary technique for the purpose of studying the biological role of fibronectin, and that the fibronectin reaction has a close relationship with malignancy and with cellular atypism of the epithelium of the large intestine.