Architecture of chicken muscles: short-fibre patterns and their ontogeny.

Abstract

Staining for motor endplates and chemical digestion of five major muscles of the domestic chicken shows that these confirm the short-fibre strap muscle paradigm. The individual fibres are spindle-shaped, terminating in gradually tapering ends. The motor endplates of the individual fibres align in cross-bands along the length of the fascicles. These bands are spaced much more tightly than are comparable bands in mammals; unlike the condition in mammals, many fibres are longer than twice the interband spacing. The spacings between bands differ by more than a factor of five along the length of each muscle. The proportions among bands remain relatively constant. These proportions are not affected by the degree of muscular contraction, nor do they change with ontogeny, suggesting that the arrangement is established before hatching.