Electron microscopy of renal and ocular changes in virus-induced diabetes mellitus in mice.

The eyes, kidneys and pancreas of mice (SJL/J) infected with encephalomyocarditis virus were examined by light and electron microscopy. Diabetic mice with the longest duration (6 months) of diabetes showed marked renal and ocular alterations. Fasting blood glucose levels were 17.8-21.9 mmol/l and glycosuria was present. Clinically, based on ophthalmoscopy and fluorescein angiography, retinal vessels were normal. Histologically, moderately decreased numbers of pericytes were noted following trypsin digestion. The basement membrane of inner retinal vessels showed significant thickening in diabetic mice. Corneal epithelial oedema was present and surface microvillus projections were decreased compared with control mice. The kidneys of the same animals showed nodular and diffuse glomerulosclerosis and mesangial thickening. Electron microscopy showed excessive accumulation of basement membrane-like material in the mesangium and the peripheral glomerular region. Histologically, moderate to advanced kidney disease was associated with relatively early retinopathy.