Mesangial bridges. A mode of progression in diabetic glomerulosclerosis.

Electron microscopic examination of the renal biopsy material obtained from a 35-year-old diabetic patient revealed subdivisions of glomerular capillaries into several branches by dendritic mesangial projections built between the mesangium and peripheral loop, a similar process which was described as mesangial bridges in a chronic phase of masugi nephritis. In comparison with those in experimental animals, mesangial bridges in the present case appeared rather solid with matrix formation, most presumably depending on long duration of the disease state in the diabetic patient. This process may represent a more complicated type of lesion invariably accompanying the nodule formation and is assumed to be an irreversible lesion ultimately undergoing segmental obliteration of glomerular capillaries.