Material and Method: Twelve male Sprague-Dawley rats were used. Each diabetic rat (n = 8) was induced by an intraperitoneal injection of STZ (60 mg/kg) in citrate buffer (pH 4.5). Control rats (n = 4) were injected intraperitoneally with the same amount of the buffer. The animals were sacrificed at 20 weeks after the injections. The kidneys were processed for conventional light microscopy (LM) and vascular corrosion cast technique with scanning electron microscopy (SEM).

Results: Under LM, it was found that the glomerular sizes intensively decreased in the long-termed diabetic rat. The thickening of Bowman’s basement membrane was demonstrated. Additionally, there were macrophages and capsular drop lesions in renal corpuscles of long-termed diabetes. The sizes of proximal and distal tubules were markedly destroyed, when compared to the control. Moreover, the epithelial necrosis of vacuolated renal tubules was observed. By using vascular corrosion cast with SEM, the glomerular microvascular sizes in the long-termed diabetes were significantly decreased that corresponded to the result under LM. Furthermore, the size of peritubular capillaries decreased. Concerning to vasa recta in the long-termed diabetes, these vessels ran tortuously and decreased in size.

Conclusion: Renal microvascular changes, observed in STZ-induced diabetic rats, mimic human diabetic nephropathy (DN). Additionally, the pathological changes of the renal tubules were investigated. Therefore, the present study provides an important basic knowledge for understanding the processes in developing DN, as well as for further study of the therapeutic treatment.

Keywords: Renal microvasculature, Diabetic nephropathy, Streptozotocin, Vascular corrosion cast, SEM