A scanning electron microscopy study of ultrastructural changes in the colonic mucosa of patients with large bowel tumours.

Scanning electron microscopy (SEM) has been used to compare the appearances of the colonic mucosal surface and overlying mucus layer of patients with normal colons, adenomatous polyps and colorectal carcinoma. The normal colonic mucosa had a characteristic orderly arrangement of crypts and was completely covered by an intact mucus layer. Epithelial and cryptal irregularities were seen on the surface of both polyps and carcinomas, and, in addition, the mucus layer was fragmented, leaving areas of the underlying epithelium exposed. These changes were more marked in colorectal cancers than in polyps and were present to a lesser degree in the apparently normal mucosa adjacent to tumours. The findings indicate that SEM can detect minor subtle irregularities on the surface of the colon and so may be useful in detecting pre-neoplastic and early neoplastic changes.