Scanning electron microscopic observation of the architecture of collagen fibres in chicken M-iliotibialis lateralis

1. The collagen architecture of M. iliotibialis lateralis in chicken was ob served under the scanning electron microscope after muscle maceration in Na OH. 2. Immunohistochemical methods showed Type I and III collagens to be distri buted over both perimysium and endomysium. 3. Thick perimysium around secondary myofibre fasciculi was composed of man y large longitudinal collagen bundles and a few small circumferential bundl es. In contrast, thin perimysium around primary myofibre fasciculi showed m ainly circumferential bundles. 4. Endomysium had a honeycomb-like structure and consisted of a fine collag en mesh, its main fibre striation being circumferential. 5. It is suggested that functional demand differs between thick perimysium and thin endomysium.