[A study of binding sites of lectins in colorectal adenomas and carcinomas: the optical and electron microscopical findings].

The mucin alterations associated with the progress of cellular atypia of the colorectal mucosa were investigated by light and electron microscopy using lectin-histochemical technique with DBA and PNA. The samples showing positive staining in the more than one-third areas of the colonic epithelial mucosa were scored as positive reaction. The DBA positive reaction was found 100%, 95.8% and 45.7% in the normal mucosa, adenoma and carcinoma, respectively. On the other hand, the PNA positive cases increased with the grade of malignancy; 18.2%, 58.5% and 97.1% respectively. The DBA binding sites were found in the mucin of the goblet cells of the normal and adenomatous epithelia. The PNA positive sites were localized in the supranuclear portion of the normal mucosa and adenoma while in the epithelia of the carcinoma the PNA positive areas were found in the intraglandular substance and cell apex. With the electron microscopy the PNA binding sites were detected in the cis cistern of Golgi apparatus in the normal and adenomatous epithelia and in the apical membrane in the epithelia of the carcinoma. It is suggested that the PNA binding activity is a useful marker to detect the adenomas with the high risk of malignant transformation.