Histopathological Evaluation of Bile Duct Ligation-Induced Liver Injury

All tissue samples were fixed in 10% neutral formalin solution and embedded in paraffin blocks. Serial slices of 4-5 μm thickness were obtained from paraffin blocks. All sections were deparaffinized and stained with hematoxylin and eosin for morphological examination. Liver injury due to BDL was evaluated semiquantitatively for the typical histopathological findings by light microscopy by a blinded pathologist. Histopathologic findings were as follows: portal inflammation, lobular inflammation, bile duct proliferation, and necrosis, which were scored as follows: 0: no, 1: mild, 2: intermediate, 3: manifest, and 4: severe. Additionally, bile-induced infarction was scored according to the degree of damage: 0: no infarction, 1: mild infarction, 2: intermediate infarction, 3: manifest infarction, and 4: severe infarction. Fibrosis was graded as follows: 0: no fibrosis, 1: portal enlargement, 2: septal formation, 3: manifest bridging fibrosis, and 4: cirrhosis. Microscopic images were obtained from each study group. Tissue samples were stained with immunohistochemical stains to show MCs. Slices of 4-5 μm thickness were taken from the paraffin blocks. Sections were deparaffinized and stained with “MC tryptase” mouse monoclonal primary antibody in an automatic immunohistochemical staining device after preapplication with citrate pH:7.0 by the microwave heating method. Reactive cells were counted in every high-power area (HPA) to determine MCs by a blinded pathologist.