Cystitis cystica: an electron and immunofluorescence microscopic study.

Cystitis cystica was studied with the aid of electron and immunofluorescence microscopy. By electron microscopy, the epithelium demonstrated morphologic features suggestive of an active metabolism. Secretory-type granules were seen in the cytoplasm just beneath the luminal membrane of surface columnar cells. Microvilli of the plasma membrane also were seen at the luminal surface. Rough endoplasmic reticulum and Golgi apparatuses were present. The cells were rich in mitochondria. By immunofluorescence microscopy, IgA, secretory piece and IgM were localized in the epithelial cells, especially at the luminal surfaces. IgG was occasionally found. These findings contrast markedly with the transitional cells and their relatively scanty content of secretory-type organelles. In addition, they may explain the large amounts of IgA in the urine of patients with cystitis cystica.