Abstract
This study was conducted to investigate the histologic changes of the kidney, urinary bladder, testis, seminal vesicle and prostate gland of rats of various ages (6,12, and 18 months old). Results illustrated variable changes of the kidney represented by congestion of renal capillaries, acute tubular necrosis, shrinkage of glomerular tuft, and degeneration in the tubular epithelium of the 6,12 and 18 months old rats, the morphometric changes of the glomerular diameter decreases with advanced age. The lesions of the urinary bladder are characterized by hyperplasia of the epithelial lining, papillae into the lumen, hypertrophy of muscle fibers, desquamation of epithelium, cystitis in addition to thickening of the mucosa and hyalinization of muscle fibers of the 6,12 and 18 months old rats. The thickness of the bladder wall showed significant changes increase at (P≤0.05) with age, while morphometric analysis did not show any age-related changes in the bladder muscle thickness. In testis, there were congestion of blood vessels, a spermia, degeneration of the spermatocytes and spermatozoa, and thickening of interstitial and hyperplasia of leydig cells of the 6,12 and 18 months old rats. The wall thickness of the Seminiferous tubule increases with age and basement membrane thickness and tubular diameter decreased with age. The seminal vesicle of the 6,12 and 18 months old rats revealed hyperplasia of glandular epithelium. Lesions of the prostate gland of 6,12 and 18 months old rats showed epithelial hyperplasia which extended as finger-like projections and the presence of variable amounts of a colloid substance.

Key words: Histological changes, Morphometric changes, Aging, Rats, Seminal vesicle, Prostate