myofibrils
Myofibrils - shrink filaments, filament macrocomplexes in the form of mini-filaments. The filaments in them are very regular, they overlap in a hexagonal pattern. They are: ▪ thin filaments consisting of the following proteins: actin, tropomiosin and troponin; ▪ thick filaments, which contain powerful myosin protein. Myofibrica is a fundamental component of myocytes that form the muscle tissue. Observing myofibrils under an electron microscope, they can be seen in the presence of repetitive fragments containing alternately arranged high-activity areas called light bands, or I, and fragments where the most is myosin, called dark bands or A. The myofibreliel segment is bounded by two Z films is half-band I, band A, and half of the next band I, is called sarcomer. It is the basic structural and functional unit of shrinkage.