Histology and collagen. (a) Top panel: histology sections from bile duct ligated (BDL) or sham-operated rats stained with Sirus Red as viewed by conventional light microscopy (top row) and after masking (bottom row), showing red colour in areas with collagen and blue in the parenchyma. Bottom panel: Masked histology sections for quantifying total collagen content (red colour) in the liver. (b) Correlation of serum procollagen type I N-terminal propeptide (PINP) and percentage liver content collagen. (c) Total collagen quantified by Visiopharm software for each group.