Distribution of Myofiber Types in the Hip and Thigh Musculature of Pigs

抄録

Type I myofibers are concentrated in the deep portions of the muscles situated cranially in the thigh and distributed sparsely in the caudally situated muscles in quadrupeds. The distribution of myofiber types in the hip and thigh musculature of pigs was examined. Myofibers were classified into type I, type II A, and type II B myofibers by differences in histochemical reactivity for myosin ATPase and reduced nicotinamide adenine dinucleotide dehydrogenase. Type II B myofibers were distributed more greatly in the superficial portions than in the deep portions in the hip and thigh musculature. Type II A myofibers varied less in proportion than did types I and II B myofibers. Type I myofibers were distributed greatly in the gluteus profundus muscle and the deep portion of the quadriceps femoris muscle situated cranially in the thigh. In addition, type I myofibers were concentrated in the craniolateral portion of the semimembranosus muscle situated caudally in the thigh. These results show that type I myofibers are concentrated not only in the cranially situated muscle but also in the caudally situated muscle in the thigh of pigs.