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

摘要

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 pigswas examined. Myofibers were classified into type I, type II A, and type IIB myofibers by differences in histochemical reactivity for myosin ATPase and reduced nicotinamide adenine dinucleotide dehydrogenase. Type IIB myofibers were distributed more greatly in the superficial portions than in the deep portions in the hip and thigh musculature. Type IIA myofibers varied less in proportion than did types I and IIB myofibers. Type I myofibers were distributed greatly in the glutens profundus muscle and thedeep 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.