MICROANATOMY

Detailed explanation-1: -The arrangement of thick myosin filaments along the myofibrils and the cell cause them to refract light and produce a dark band which is known as an A band. The anisotropic band is composed of both thick and thin filaments. Therefore the correct answer is option (C) both actin and myosin filaments.

Detailed explanation-2: -The light bands are called I bands and contain only thin filaments. The dark bands are called A bands and contain thick and thin filaments, with the thick filaments running the entire length of the A band. Thus the length of the thick filament determines the length of the A band.

Detailed explanation-3: -The myosin filaments are called thick filament. The thick filaments in the ‘A’ band are also held together in the middle of this band by a thin fibrous membrane called ‘M’ line.

Detailed explanation-4: -The A band is the region of the sarcomere that contains the myosin (thick) filaments, regardless of overlap. This means that myosin is exclusive to the A band, but that this region contains both actin and myosin due to overlap.