Evolution of glomerular lesions in rats with spontaneous diabetes.

The development of glomerular lesions associated with ageing was investigated electron microscopically in rats with spontaneous diabetes. In young diabetic rats at eight weeks of age, there was no particular difference in ultrastructure from age-matched control rats showing an even contour of glomerular basement membrane, whereas in the diabetic rats at 12 weeks of age thickening of basement membrane with irregular protrusion of the epithelial side of lamina densa and accumulation of basement membrane-like materials in the mesangial regions could be observed. After 16 to 24 weeks of age in the diabetic rats, hemispherical thickening in addition to diffuse thickening of glomerular basement membrane was noted. The thickening of basement membrane was due to widening of lamina densa consisting of accumulation of basement membrane-materials on the epithelial side of the lamina densa, all the way along the peripheral capillary loops. These features of glomerular lesions in the diabetic rats were progressively accentuated accompanying ageing. The early glomerular ultrastructural alterations in the diabetic rats were very compatible with those seen in the elder control rats. The results indicated that the development of diabetic glomerulopathy might be destined very early in life of the spontaneously diabetic rats supposedly by their diabetic genes.