Histology of untreated and ethanol-treated OLETF and OLET rats. (A) H&E staining of liver tissues from 10- and 33-wk-old untreated OLETF rats and 30-wk-old OLETF rats treated with 10 mL of 10% ethanol for 5, 3, 2 and 1 d/wk for 3 wks. There was no histological alteration in 10-wk-old OLETF rats. Fatty degeneration and microvesicular steatosis (arrowhead) were present in 33-wk-old untreated OLETF rats. Massive steatohepatitis with numerous hepatocyte ballooning (arrow) and microvesicular steatosis (arrowhead) were present in all OLETF rats treated with ethanol, irrespective of number of days treated. (B) H&E staining of liver tissues from 10- and 33-wk-old untreated OLET rats and 30-wk-old OLET rats treated with ethanol 5 d/wk for 3 wks. No histopathological changes or fatty degeneration were seen in either untreated rats or rats treated with ethanol. Scale bars, 100 µm.