Focal and segmental glomerular hyalinosis and sclerosis in the rat.

A glomerular disease spontaneously developing in Wistar rats was studied by light and electron microscopy and by immunofluorescence techniques. The disease is characterized by the local subendothelial deposition of hyaline material leading to increase of mesangial matrix and the development of adhesions. Immunofluorescence shows deposition of complement and IgM and to a lesser degree also of IgG in these lesions. There is a constant relationship of these early changes with the vascular pole of the glomerulus. It is confirmed that female rats are resistent to the disease as are male rats fed a sodium-deficient diet. A higher protein excretion was found in normally fed male rats as compared to female rats and to rats on a sodium-deficient diet. These differences already existed before the normally fed male rats developed glomerular disease. From these studies it is suggested that an appropriate name for this disease would be focal and segmental glomerular hyalinosis and sclerosis and that hemodynamic factors could be an important etiologic mechanism. The histopathology of the disease bears a striking resemblance to focal sclerosing glomerulopathy with segmental hyalinosis sometimes found in kidneys of patients with an idiopathic nephrotic syndrome.