Morphological and histochemical changes in the mucosa of the continent ileostomy reservoir 6--10 years after its construction.

Morphological and histochemical changes in the mucosa of the continent ileostomy reservoir were studied in 13 patients who had been provided with a continent ileostomy reservoir 6--10 years before the investigation. Biopsy specimens were taken for evaluation of basal morphology, morphometry, and enzyme histochemical analyses. The villi were predominantly finger-like, but the villus height was reduced compared with normal. The crypt layer and the number of cells in each crypt were increased. The number of mitoses was normal or slightly subnormal. In comparison with biopsies taken 1 year after construction of the reservoir, there was an increase in villus height and mucosal volume and a decrease in the number of mitoses, whereas the number of cells per crypt was unchanged. The surface to volume ratio decreased progressively during the 6- to 10-year period. This decrease was partly caused by an increase of the mucosal volume. The epithelial cell layer was intact, and no changes were seen in the microvillus layer. No alarming changes in terms of dysplasia, fibrosis, or progressive atrophy were found. Histochemical investigation showed a high enzymatic activity in the epithelial cells as concerns both the oxidative metabolism and the secretory function.