Z-line

The Z-line, also called the Z-disc, is a boundary within the muscle tissue of the heart that marks the division between two neighboring sections of muscle fibers. It is a key structural feature in muscle cells, anchoring the protein filaments that allow muscles to contract. In the heart, the Z-line helps organize and align the muscle fibers to ensure efficient contractions vital for pumping blood. Under a microscope, the Z-line appears as a distinct horizontal line within muscle tissue, providing a reference point for studying muscle structure and function.