The location of three collagen types in skeletal muscle

Collagen is the major supporting tissue of skeletal muscles and these collagenous tissues have been classified on anatomical and histological grounds. Thus, the epimysium forms the outer sheath of the muscle, the perimysium surrounds the muscle fibre bundles and the endomysium surrounds each individual muscle fibre [l] . Histologically the periand endomysium are composed of fine fibres and are often referred to as reticulin. Further, the endomysium appears from electron microscope studies to be mainly an amorphous basement membrane structure PI. The existence of several chemically and genetically distinct collagens has now been established [3] . Skin, tendon and bone consist mainly of Type I collagen, hyaline cartilage Type II, foe&l skin and blood vessels mainly Type III and basement membrane Type IV collagen. Our recent chemical studies have indicated the presence of collagen Types I, III and a third form, believed to be Type IV, in bovine muscle [4] . It is possible that there is a correlation between the histological classification and these genetic types of collagen. In this study we have therefore attempted firstly, to confirm the identity of the ‘Type IV’ as basement membrane and secondly to determine the tissue-specific location of these collagens by immunofluorescence using antibodies that react specifically with the three polymorphic forms of collagen.