Ultrastructural and histochemical changes in ileal reservoir mucosa after long-term exposure to urine. A study in patients with continent urostomy (Kock pouch).

Mucosal biopsy specimens were obtained from ileal reservoirs used for urinary collection in patients with continent urostomy. Shortly after construction of the reservoir there was a reduction in villous height and an increase in crypt depth. After 2 to 3 years of observation, avillous areas were noted in the reservoir mucosa, mixed with islets of villous mucosa. Specimens from the avillous areas showed a marked decrease in height of superficially located enterocytes, with loss of microvilli and a reduction in cell organelles. The histochemically demonstrable activity of oxidative enzymes was significantly reduced in the epithelial cells. There was an increase in the number of goblet cells and autonomic nerve fibres in the crypt layer. The constant exposure to urine led to significant alterations of the ileal mucosa resulting in avillous areas mixed with villous remnants in which many of the intestinal characteristics both structurally and functionally disappear.