Histochemical fiber types in the thigh muscles of 4 chicken inbred lines.

Distribution, frequency and diameter of fiber types were ascertained in the thigh muscles of I, C, W and M chicken inbred lines. The iliotibialis posterior muscle is composed of FOG and FG types uniformly distributed over the whole muscle cross-section. Three fiber types are demonstrated in the sartorius and semimembranosus muscles. In the superficial regions, the FOG and FG types are present only. Avian SO type appears down into the depth of the muscles. The frequency of this type and FOG type gradually increases in this direction whereas the proportion of FG type decreases. Semimembranosus muscle shows generally higher percentage of FOG fibers and lower frequency of remaining two types. Differences between inbred lines in fiber type frequencies are mostly insignificant. However, the M line with the highest live and muscle weights shows larger fiber diameter of FG and FOG types than I, C and W lines.