Electron Microscopic Studies on Experimental Diabetic Glomerulosclerosis

Abstract

For the purpose of elucidating the pathogenesis of human diabetic glomerulosclerosis (DGS), glomerular structures were examined by light and electron microscopy in eighteen alloxan-diabetic rats and eleven age-matched controls. According to the duration of diabetes, these diabetic rats were divided into four groups; group 0 with less than three months' duration, group I with three months, group II with six months and group III with nine months.
Following results were obtained:
1) The main alterations in the glomeruli of diabetic rats were thickening of the capillary basement membrane and increase in the mesangial matrix, both of which were evident after three months of diabetes.
2) In group I, II and II, the measurements of capillary basement membrane width revealed that the thickening of basement membrane was statistically significant as compared with controls and that the mean width increased with the lapse of disease apart from aging process.
3) Furthermore, the grading of increase in mesangial matrix demonstrated that it had tendency to augment with the duration of diabetes.
4) In addition to these changes, thickening of the basement membrane was found in Bowman's capsules and renal tubules in some diabetic cases, and also the cytoplasm of epithelium as well as mesangial cells contained prominent cell organelles and inclusions.
5) Although no arteriolar sclerosis nor typical nodular lesions were recognized in the present experiment, the glomerular lesion was very similar to that of the diffuse type in human DGS.
From this experiment it is inferred that the main alterations in the glomeruli of diabetic rats results from the metabolic abnormality consequent upon insulin deficiency and that at least one of the primary causes of human DGS is also such mechanism