A histochemical study of myofiber types in muscle of the growing pig.

摘要: The conversion of myofiber types was studied in the masseter, trapezius, longissimus, rectus femoris and vastus intermedius muscles pigs at birth 2, 4, 8 16 weeks age. histochemical reaction for ATPase used to classify myofibers as type I (acid-stable, alkali-labile) or II (alkali-stable, acid labile). Type were divided further into categories IIA IIB. Subtypes SM, SS MS intermediate classified on basis pH sensitivity reaction. In masseter muscles, proportion decreased increased from age, little change occurred thereafter. These three had more than myofibers, regardless At trapezius both but during development, greatly while that markedly. weeks, about equal proportions l a much higher myofibers. A flow diagram developed illustrate proposed via stages identified subtypes MS, SM. Development grouped pattern association with functions muscle are discussed.