Morphology of perimysial and endomysial connective tissue in skeletal muscle.

The fibrous components of the endomysium and perimysium of various muscles from four animal species were examined by scanning electron microscopy. All muscles were qualitatively similar. Endomysium consisted of a dense feltwork of collagen fibrils completely covering individual muscle fibre surfaces. Perimysium consisted of three fibrous components, (1) coarse, crimped fibres laid down in a well-ordered criss-cross pattern, (2) a loose feltwork of non-crimped fibrils, (3) fine non-crimped bundles of fibrils with no directional organization. The perimysium showed gradation from dense sheets of collagen down to the most delicate of sheets found on every muscle fibre surface overlying the endomysium.