Electron microscopic and histological findings on urinary bladder epithelium in interstitial cystitis.

Urinary bladder epithelium was studied with electron microscope in 50 patients with interstitial cystitis (IC) and 9 controls. In addition, biopsies of 14 patients with IC were studied with special stains for the presence of bacteria or viral inclusions in the epithelium. No bacteria or viral inclusions could be demonstrated. On the basis of these and earlier negative findings it appears that simple infection of the epithelium is ruled out as the aetiology in IC. Electron microscopy demonstrated an increase in large swollen epithelial cells with decreased amount of lateral processes in half of the IC samples and inflammatory changes in the mucosa. The similarity of the ultrastructure of epithelial cells in controls and IC patients makes it improbable that the disease process originates in the epithelium. In this study special attention was paid to large cytosomes (diameter 0.4--6.0 mum) in the epithelial cells. These contained small vesicular bodies (diameter 0.04--0.2 mum) and lipid droplets, and were found in controls as well as in IC patients.