Collagen localization in normal and fibrotic human skeletal muscle

The distribution of types I to IV collagen, types I and III p-N collagen, and fibronectin in human skeletal muscle was studied by immunofluorescence using purified antibodies to those proteins. In normal muscle, types I and III collagen, types I and III p-N collagen, and fibronectin were localized in the endomysium and perimysium. Type IV collagen was restricted to basement membrane. Type II collagen was not present. In Duchenne's musclar dystrophy and dermatomyositis/polymyositis (DM/PM), the prominently increased endomysial and perimysial fibrosis consisted of types I and III collagen, types I and III p-N collagen, and fibronectin. In DM/PM, thickening of the walls of perimysial venular and arteriolar vessels was associated with accumulation of types I and III collagen, types I and III p-N collagen, and fibronectin, as well as type IV collagen. There was no disease-specific accumulation of collagen, p-N collagen, or fibronectin.