Distribution of type I-, IIA- and IIB-fibers in m.longissimus dorsi and m.semitendinosus in swinIA- and IIB-fibers in m.longissimus dorsi and m.semitendinosus in swine of various age
Szentkuti, L.; Cassens, R.G.
Deutsche Tierärztliche Wochenschrift 85(1): 23-27
1978
ISSN/ISBN: 0341-6593 PMID: 74315 Document Number: 131588
The distribution of fibres was studied by using three modifications of the myosin-ATPase-staining procedure. In both muscles the fibre types were distributed in a certain pattern within the fascicular boundaries. The centre of a fascicular boundary was composed of type I fibres, which were surrounded in the next area by type IIA fibres and at the outer ring of the fascicle by IIB fibres. The interfascicular arrangement of fibre types and the number of fibre types per fascicle varied according to muscle, location within muscle and age of pig. The number of type I fibres increased in both muscles during growth of the pig and decreased after sexual maturation of the pigs. There were no fibres of type I in some fascicles of the longissimus dorsi and in all fascicles of the caudal portion of semitendinosus of 2-year-old pigs.