Figure 1.

A fragment of an electron micrograph of a transverse section of a muscle fiber in the low temperature, relaxed state. Thick and thin spots correspond to myosin and actin filaments, respectively. Examples of elementary unit cells for individual filaments are shown: a hexagonal myosin-centered super-lattice cell (on the left) and a triangular actin-centered cell (on the right). Open circles show the software calculated positions of the centers of mass of myosin filaments in the cells. Black solid circles cover the central filaments in the cells.