The Structure of the Muscle Bunbles as Organized Unit in the Muscle Tissues ot the Cattles

Abstract

The structure of muscle bundles in the cattle was studied histologically for thepurpose of evaluation of meat quality.Five Japanese Black (310 kg in average dressed-weights) and three Japanese Shorthorn steers (370 kg in average dressed-weights) were used. One hundred of samples were prepared from 88 kinds of muscles of cooled carcasses. The samples were fixed in Ca-formalin. Cross and longitudinal sections were cut from paraffin-embedded samples. Average area of muscle fibers in sections was measured by the Texture Analysis (TAS plus: Leitz Co.).It was observed that the size of the muscle fibers was larger in the big muscles than in the small muscles. The size of the muscle fibers was large in the muscle of standard muscle group 1.The primary muscle bundles were present as the structural unit of the secondary muscle bundles.In the center portion of the secondary muscle bundles, arterioles and venules were supplied from the blood vessels running between secondary muscle bundles. The vessele run longitudinally for 2 mm to 5 mm through the center of the secondary muscle bundles. Adipose tissues were formed around the vessels within the secondary muscle bundles. The structure of the secondary muscle bundles, particularly in the muscles with larger muscle fibers, was observed in the two breeds.The findings suggest that the intrinsic supply of blood vessels within muscle bundles results in the formation of adipose tissue of cattle muscle.