MICROANATOMY

Detailed explanation-1: -The I bands contain only thin (actin) filaments, whereas the A bands contain thick (myosin) filaments. The myosin and actin filaments overlap in peripheral regions of the A band, whereas a middle region (called the H zone) contains only myosin.

Detailed explanation-2: -These dark and light bands are called A-bands and I-bands respectively. The A-band is made up of myosin filaments whereas the I-band is made up of actin filaments alone.

Detailed explanation-3: -A bands (or anisotropic bands): It is also called the dark band and contains the whole thick filament (myosin). I bands (or isotropic bands): it is called the light band that contains only the thin filament (actin). The thin filament lies between the two thick filaments.

Detailed explanation-4: -In physiology, isotropic bands (better known as I bands) are the lighter bands of skeletal muscle cells (a.k.a. muscle fibers). Isotropic bands contain only actin-containing thin filaments.

Detailed explanation-5: -The thick filaments are anchored at the middle of the sarcomere (the M-line) by a protein called myomesin. The lighter I band regions contain thin actin filaments anchored at the Z-discs by a protein called -actinin.