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, as seen in the images to the right.
A trichrome-stained liver biopsy demonstrating normal tissue architecture.
