Two cases of tubulovillous adenoma and adjacent colonic mucosa were st
udied in which intestinal spirochaetosis had heavily colonized the non
-neoplastic but not the neoplastic epithelium. Ultrastructural and his
tochemical studies were performed and we postulate that the reason for
this disparity is the normal microvillous pattern of the non-neoplast
ic epithelium which facilitates colonization by the spirochaetes.