The H-zone in the skeletal muscle fibre is due to

The H-zone in the skeletal muscle fibre is due to
  1. the absence of myofibrils in the central portion of A-band
  2. the central gap between myosin filaments in the A-band
  3. the central gap between actin filaments extending through myosin filaments in the A-band
  4. extension of myosin filaments in the central portion of the A-band

Solution

$\mathrm{H}$-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.

Asked in: NEET 2013 (All India)

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