Skeletal muscle. Coloured scanning electron micrograph (SEM) of a freeze-fractured transverse section through a bundle of skeletal (or striated) muscle fibres. The banding patterns on the fibres arise from the regular arrangement of the microscopic fibres (myofibrils) that comprise the structure of a fibre. Skeletal muscle is under voluntary control, and is responsible for the movement of long bones. Each fibre is surrounded by a connective tissue sheath (endomysium, pink) and blood vessels (holes). The blood vessels have been emptied of blood. Magnification: x1000 at 6x7cm size.