Abstract: Objective: To investigate the dynamic pathological characteristics of kidney in the db/db mice with type 2 diabetes mellitus and to clarify the pathogenesis and development mechanism of diabetic nephropathy,and to provide the experimental evidence for the further study on diabetic nephropathy. Methods: The male SPF db/db mice aged 7-8 weeks were selected as model group (n=16) and the db/m mice with the same ages were selected as control group(n=16).The body weights and levels of fasting blood glucose(FBG) of the mice were detected after 8,16, and 32 weeks.Then eight mice in each group were sacrificed and the kidney tissue was dissected at 8,16 and 32 weeks.HE and Masson staining were used to observe the pathomorphology of the kidney tissue; the ultrastructures of kidney tissue were observed under electron microscope. Results: Compared with normal group,the body weights of the mice in model group at 8,16 and 32 weeks were significantly increased(P<0.01),the FBG levels were significantly increased(P<0.01),and the double kidney indexes were significantly decreased(P<0.01);the double kidney index of the mice in model group at 32 weeks was lower than that at 16 weeks(P<0.05).The HE and Masson staining results showed that the morphological changes of kidney tissue of the mice at 16 weeks were significant,the glomerular volume was expansion and the kidney tubular epithelial cells were edema,which turned serious at 32 weeks.A large number of blue dye substances in the kidney tissue was found.Under electron microscope,the glomerular basement membranes got thickened,the foot processes got fused and the number of mitochondria in kidney tubular epithelial cells was reduced and swell was found in the mice in model group at 16 weeks;the lesions in the kidney tissue were serious at 32 weeks,and the collagenous fiber was visible at 32 weeks. Conclusion: The pathological changes in the kidney tissue of the db/db mice at 16 weeks are significant,such as glomerular basement thickening and footwork fusion.The kidney tissue of the db/db mice at 32 weeks shows prominent fibrosis.

Key words: fasting blood glucose, db/db mice, type 2 diabetes mellitus, HE staining, Masson staining