For light microscopic analysis of liver histology, the paraffin-embedded liver tissues were cut into 4-μm sections, and standard hematoxylin-eosin (H&E) staining was performed. Hepatic fibrosis was assessed by Masson stain. Ten 200× light microscopic fields were viewed on each section and scored for the severity of hepatic steatosis, inflammation and fibrosis according to the following criteria [32 (link)]: For hepatic steatosis: grade 0, no fat; grade 1, steatosis occupying less than 33% of the hepatic parenchyma; grade 2, 34–66% of the hepatic parenchyma; grade 3, more than 66% of the hepatic parenchyma; for inflammatory cell infiltration: grade 0: none; grade 1, 1–2 foci/field; grade 2, 3–4 foci/field; grade 3, more than 4 foci/field. The staging of hepatic fibrosis was investigated by Masson staining as follows: 0, none; 1, mild, zone 3, perisinusoidal; 2, moderate, zone 3, perisinusoidal; 3, portal/periportal; 4, bridging fibrosis [32 (link)].
Mitochondria of the liver were assessed by transmission electron microscopy (TEM), which as performed by the Electron Microscopy Center of the Shanghai Jiao Tong University School of Medicine.