Structural diversity in muscle fibres of chicken breast.
Chicken breast muscle is usually considered to be a relatively homogeneous white muscle and has therefore been widely used for studies of muscle proteins. In a previous study, however, we have found different M-region structures in different fibres from this muscle. Because of this result, we have now carried out a combined histochemical and ultrastructural survey of this muscle. In particular, we have made use of large transverse cryo-sections that include most of the muscle cross-section. Although the white region is fairly homogeneous in fibre content according to normal histochemical criteria (mATPase), we have found that there is a gradation of fibre structure across the muscle. The bulk of the muscle stains conventionally for Type-II fibres according to mATPase tests (the "white" part) but, in the small "red" part of the muscle, there are also Type-I fibres together with the Type-II fibres. Superimposed on this division into Type-I and Type-II fibres are variations in fibre size, oxidative and glycolytic staining properties, and variations of Z-band width and M-band structure; there is no strict correlation among any of these parameters. The apparently uniform staining across most of the muscle when tested for myofibrillar ATPase may be a misleading indicator of fibre properties.
Edman
A C
AC
Department of Anatomy, University of Umeå, Sweden.
Lexell
J
J
Sjöström
M
M
Squire
J M
JM
D000251:Adenosine Triphosphatases / Q000032:analysis; D000818:Animals; D002645:Chickens / Q000033:anatomy & histology* / Q000378:metabolism; D006651:Histocytochemistry; D008854:Microscopy, Electron; D010088:Oxidoreductases / Q000032:analysis; D010369:Pectoralis Muscles / Q000201:enzymology / Q000648:ultrastructure*
D010088:Oxidoreductases; D000251:Adenosine Triphosphatases