[Structure and functional significance of the thick filament]

New models of the thick filament structure and muscle contraction are proposed in the work. Association of myosin molecules into filament occurs by intertwisting between them. The model is in good consistency with experimental data. A computer analysis of the widely accepted concept of parallel packing of myosin molecules is presented. It is shown that the rowing movement of crossbridges resulting from parallel packing is, on the one hand, impossible in terms of sarcomere construction, and on the other hand, is in conflict with available experimental data. The crossbridge movement by unwrapping easily agrees with recent experimental data as well as given possibility to interpret such phenomena as the change of the myofilament dimensions under certain conditions or step-wise manner of sarcomere contraction.