A liver biopsy (trichrome stain) demonstrating an increase in type I collagen in a patient with bridging portal fibrosis.
Liver biopsy (Masson's trichrome stain) demonstrating increased collagenous tissue in a patient with inactive cirrhosis.
Type I collagen is abundant in the human body. Its primary activity is to resist tension, remaining firm. Type I collagen can be found in organs such as skin, bone, and the liver. In histology, the trichrome stain is used to confirm the presence of type I collagen and is commonly used to interpret liver biopsies. Normal liver biopsies demonstrate trichrome stained collagen in the portal tracts and around the central vein, as shown in the image below. An abnormal trichrome stained liver biopsy will demonstrate an excess in type I collagen, which is referred to as fibrosis, seen in the images to the right.
A trichrome stained liver biopsy demonstrating normal tissue architecture and favorable tissue cassetting.