Ultrastructural and immunohistochemical similarities between glomerular arteriolar and mesangial lesions in experimental diabetes.

It has thus far been speculated that plasma proteins have leaked and accumulated in diabetic expanded mesangium. We have previously shown that glomerular arteriolar hyalinosis has frequently occurred and has consisted of basement membrane-like extracellular matrix in alloxan diabetic rats. In the present study, the two diabetic glomerular lesions, arteriolar hyaline nodules and increased mesangial matrix, were comparatively evaluated by means of electron microscopy and immunohistochemistry. It was revealed that both of these lesions contained, in common, finely particulate extracellular matrix mingled with cytoplasmic fragments, and exhibited intense immunoreactions for IgG and IgM. It is indicated that both types of diabetic glomerular lesions are essentially of the same nature.