the male beagles were divided into two groups vasectomized and sham-operated groups (n=5 in each). histopathological, ultrastructural, and tunel evaluation of the changes in the testis, epididymis, and ductus deferens of each animal were conducted 12 months after surgery. the mean lumen diameter, cellular thickness, mean interstitial distance, and lumen area fraction of each seminiferous tubule and ductus epididymis were measured by stereological analysis.