Electron microscopic studies on IgA nephropathy.

Abstract

We carried out electron microscopic studies on renal tissues from 9 patients with IgA nephropathy. Electron dense deposits were present in the mesangial area in all cases, subendothelial deposits in 4, and subepithelial deposits in only one. In basement membrane, segmental swelling and rarefaction of basement membrane substance were observed. In some cases the degenerated basement membrane substance protruded through the dilated endothelial fenestration into capillary lumina. Focal splitting, attenuation, mouse eaten appearance, and herniation of basement membrane were seen in a high incidence. Mesangial cells possessed well developed rough endoplasmic reticulums and polysomes. In the peripheral areas of mesangial cell cytoplasm, there was accumulation of electron dense substance and this was occasionally continuously present in the mesangial matrix. There was segmental swelling of endothelial cell cytoplasm, resulting in loss of fenestration. Epithelial cells had well developed rough endoplasmic reticulums and polysomes. Segmental foot process fusion was seen, and these processes, regardless of fusion, became electron denser in the area close to the basement membrane. Multivesiculated bodies were present in all cases in the epithelial cells and in 7 cases in the endothelial cells. Spherical microparticles were present in 3 cases in the urinary space or between the basement membrane and the epithelial cells.