The I bands of a sarcomere contain which type of filaments?

The I bands of a sarcomere are made up exclusively of thin filaments, which primarily consist of actin. These regions appear light under a microscope and are critical for muscle contraction. As the muscle contracts, the thin filaments slide over the thick filaments (comprised of myosin), leading to the shortening of the sarcomere.

The uniqueness of the I bands lies in their composition; they do not contain thick filaments, which are found in the A bands. This distinction is essential for understanding how muscle fibers interact during contraction. The presence of only thin filaments in the I bands means that they play a vital role in the structural and functional dynamics of muscle tissue, allowing for effective contraction by enabling the sliding filament mechanism.

In summary, the I bands focus solely on thin filaments, making that the correct choice for this question.