Ultrastructural and functional changes of the proximal tubular epithelial cells in the renal cortex from spontaneously diabetic KKAy mice

To investigate the morphological and functional changes of epithelial cells of proximal tubules in the early stage of diabetic nephropathy, we examine d the ultrastructural changes of proximal convoluted tubular cells in spont aneously diabetic KKAy mice. KKAy mice already showed significant elevation of urinary albumin excretion at 16 weeks of age. Examination revealed that lysosomes were increased in number and conspicuous in the epithelial cells of the proximal convoluted t ubules from KKAy mice at 40 weeks of age when compared to control C57BL mic e. Furthermore, endogenous IgG was detected in the lysosomes of proximal tu bular cells from KKAy mice. These findings suggested that reabsorption activity was elevated in the pro ximal tubules of KKAy mice at 40 weeks of age.