Ultrastructural changes in the small intestinal epithelium after total resection of the colon

The aim of the study was to analyze ultrastructural changes in the mucosa of the small intestine after total resection of the colon in 29 patients (familial polyposis in 21, ulcerative colitis in 8). We studied specimens of the small intestinal mucosa obtained from ano- and rectoscopy. The specimens were routinely processed for transmission electron microscopy. Early after the operation (up to 4-5 months) we observed marked structural disorders of the mucosal epithelium and regenerative cell atypia (dysplasia-like changes). At 6 months after the operation we found rapidly progressing normalization of the epithelial mucosa and its mimicking the epithelium of the colon: increased amount of mucous cells, formation of vacuolized cells, almost complete atrophy of microvilli on the surface of enterocytes, increase of the intercellular space (retention space). Foci with dysplasia features were quite numerous in group I, in contrast to group II where they were sporadic.

the epithelium of small intestinal mucosa has the ability of convergence towards the epithelium of colon.