Elastin in bovine Semitendinosus and Longissimus dorsi muscles

The structural organization of elastin present in bovine semitendinosus and longissimus dorsi muscles was examined using light and scanning electron microscopy. Qualitatively, both muscles were found to have the same organization of the two structural forms of elastin present. Coarse elastin fibres (5-10 μm diameter) were found in the epimysium and perimysium, aligned with the long axis of the muscle fibres. In addition, finer elastin fibres (1-2 μm diameter) were found in the epimysial and perimysial sheets of collagen. These finer elastin fibres approximated the course of the collagen fibres, i.e. at an angle to the muscle fibre long axis. Quantitatively, the semitendinosus muscle epimysium and perimysium contained very heavy deposits of the coarse elastin fibres and nearly every sheet of perimysium, even the thinest, contained the fine elastin fibres. By comparison, less of the coarse elastin was present in the longissimus dorsi epimysium and it was quite rare in the perimysium. The finer elastin fibres were, however, reasonably common. The significance of this structural arrangement is discussed in relation to muscle function and to meat toughness assessment.