Effect of quercetin on liver of aged male rats. Histological structure of liver of 3 months old control rats (A), 3 months old treated liver (B), 30 months old saline treated rat (C) and 30 months old quercetin-treated rat (D). Note the vesicular nuclei (black arrows), cellular infiltration (**), dark nuclei (white arrow), vacuolated hepatocytes (black arrowhead) and congestion of the central vein (*). Stain: hematoxyline and eosin.