What component is responsible for the striated appearance of skeletal muscle?

The striated appearance of skeletal muscle is primarily due to the arrangement of sarcomeres, which are the fundamental contractile units within myofibrils. Sarcomeres are composed of thick (myosin) and thin (actin) filaments that span the length of the muscle fibers. The alternating patterns of these filaments create the light and dark bands viewed under a microscope, giving skeletal muscle its characteristic striated appearance.

While myofibrils contain multiple sarcomeres arranged in series, it is the individual sarcomere structure and their alignment that are directly responsible for the striations. The myofibrils aggregate several sarcomeres together, but it is specifically their composition and alignment that create the visible striations recognized in skeletal muscle tissue.

The endomysium and epimysium, on the other hand, are connective tissues that surround the muscle fibers and entire muscles, respectively. They do not contribute to the striated appearance but play important roles in supporting the muscle structure and providing pathways for nerves and blood vessels.