Ultrastructural studies of renal peritubular amyloid experimentally induced in guinea pigs. II. Tubular epithelial cells

The ultrastructure of cells of the renal tubule and its relationship to subepithelial amyloid deposits were studied in experimentally induced amyloidosis in guinea pigs. Amyloid fibrils were demarcated primarily between the epithelial cell and its basement membrane. Basal plasmalemmal infoldings were diminished whenever the cell abutted amyloid. Pocket‐like plasmalemmal invaginations, associated with tufts of well‐oriented amyloid fibrils, were found occasionally. Intracellular membrane‐bound amyloid fibrils, fibrils in the extracellular space between two epithelial plasma membranes, and fibrils surrounded by basement membrane were also seen on rare occasions. These findings are discussed in relation to clinical features of renal amyloidosis.