Which of the following structures marks the boundary between adjacent sarcomeres in skeletal muscle tissue?

• A. Z disc (Z line)
• B. H zone
• C. M line
• D. A band

Answer: (A)

Verified step by step guidance

1. Understand the structure of a sarcomere: A sarcomere is the functional unit of skeletal muscle tissue, composed of repeating units of actin (thin filaments) and myosin (thick filaments). It is bounded by specific structures that define its limits.
2. Learn the role of the Z disc (Z line): The Z disc is a dense protein structure that marks the boundary between adjacent sarcomeres. It anchors the thin filaments (actin) and connects sarcomeres end-to-end, ensuring structural integrity during muscle contraction.
3. Clarify the function of the H zone: The H zone is the central region of the sarcomere where only thick filaments (myosin) are present. It does not mark the boundary between sarcomeres but is part of the internal structure of a single sarcomere.
4. Understand the M line: The M line is located in the center of the sarcomere and serves as an anchoring point for the thick filaments. It does not define the boundary between sarcomeres.
5. Learn about the A band: The A band is the region of the sarcomere that contains the entire length of the thick filaments, including areas of overlap with thin filaments. It is not involved in marking the boundary between sarcomeres.