$\mathrm{H}$-zone in skeletal muscle is the central gap between actin filaments extending through myosin filaments in the A-band. Alternate arrangement of dark and light bands gives the striated appearance to a skeletal muscle. At the centre of A-band, a comparatively less dark zone called $\mathrm{H}$-zone is present. In the centre of $\mathrm{H}$-zone, M-line is present, formed by the threats that connect the myofilaments.