Striated Muscle-Thyrohyoid Muscle

The characteristic striation is base d on the structure and arrangement of the myofibrils, which traverse the sarcoplasm lengthwise. This longitudinal section of the thyrohyoid muscle shows the parallel orientation of the myofibrils and the resulting fine longitudinal striation. There are alternating light and dark bands, with the dark bands being wider than the light ones. The dark cross-striations appear strongly birefringent in polarize d light (anisotropic,  A -bands). The light bands are refrainment ( isotropic, I-bands). Inside the I-bands are very narrow anisotropic bands with a larger refractive index (Z-bands or intermediary layer). In suitable preparations, a very thin M-band  (center membrane) is discernible inside the A-bands. The layers between consecutive Z-bands are called sarcomeres . These are the functional units of myofibrils. It should be noted that the nuclei are locate d at the cell periphery 1 . The (blue-stained) endomysium 2, which contains capillaries and nerve fibers, should also be noted.

1 Nucleus of a skeletal muscle fiber

2 Endomysium

Stain: azan; magnification: × 1125

References

Kuehnel, W.(2003). Color Atlas of Cytology, Histology, and Microscopic Anatomy. 4^th edition . Institute of Anatomy Universitätzu Luebeck Luebeck, Germany . Thieme Stuttgar t · New York .