Kidney aging is a normal physiological process associates with various molecular, morphologic and functional changes in the kidney tissues. This work was designed to study microscopically the structural changes in the kidney tissue of aged rats compared to young rats.
Male Sprague–Dawley rats were used 10 young rats (4 months) and 10 aged rats (24 months). Rats were transcardially perfused with 4% paraformaldehyde. The kidneys were post fixed for 24 hours in 4 % PFA then proceeded for normal histopathology and light microscopic examination.

Kidney tissue of aged rats showed serious morphological changes such as; segmental glomerulosclerosis, pericapsular fibrosis, tubulointerstitial fibrosis, perivascular fibrosis, inflammatory cell infiltration, tubular dilatation, intra-tubular cast formation and tubular atrophy. These changes were compared to the normal histological appearance of glomeruli, tubules, interstitium, blood vessels of young rat kidneys. In addition, the kidney tissue of the aged rats showed compensatory glomerular hypertrophy, tubular hyperplasia and endothelial proliferation.

Renal aging involves several degenerative changes in kidney structure and these alterations interfere with the physiologic functions and end with chronic renal failure.