The ultrastructural features of the intrinsic lingual muscles in the frog were investigated. The pieces obtained from the anterior part of the tongue were fixed in 3% gluteraldehyde and postfixed in 0.1% osmium tetroxide. Ultrathin sections stained with uranyl acetate and lead citrate were examined in a JEOL-100SX electron microscope. The muscle fibers were irregular in shape. The sarcoplasm was occupied largely by the myofibrils. In the same muscle fiber, longitudinal, transverse and oblique sections of the myofibrils were observed. Thus, regular transverse striation was prominent in some areas. In these areas, Z lines, I bands and A bands were distinguishable. H zone was hardly visible. M line was not prominent. Sarcosomes were not arranged in linear chains between the myofibrils. Triads including terminal cisternae and T-tubules were located at Z disks. The caveolae were observed as subsurface vesicles or as small groups within the cytoplasm.

The ultrastructural features of the intrinsic lingual muscles in the frog were investigated. The pieces obtained from the anterior part of the tongue were fixed in 3% gluteraldehyde and postfixed in 0.1% osmium tetroxide. Ultrathin sections stained with uranyl acetate and lead citrate were examined in a JEOL-100SX electron microscope. The muscle fibers were irregular in shape. The sarcoplasm was occupied largely by the myofibrils. In the same muscle fiber, longitudinal, transverse and oblique sections of the myofibrils were observed. Thus, regular transverse striation was prominent in some areas. In these areas, Z lines, I bands and A bands were distinguishable. H zone was hardly visible. M line was not prominent. Sarcosomes were not arranged in linear chains between the myofibrils. Triads including terminal cisternae and T-tubules were located at Z disks. The caveolae were observed as subsurface vesicles or as small groups within the cytoplasm.