Answer:
Sarcomere
Explanation:
A myofibril or muscle fiber under an electron microscope shows alternate light band and dark bands. These bands give the skeletal muscle and cardiac muscle a striated appearance. The light band is called the I- band or isotropic band, and the dark band is known as A- band or anisotropic band. In the center of the I-band Z-line is present. It is discovered from a German term Zwischenscheibe (between the disc). The portion of myofibril between one Z-line to the next Z-line is called sarcomere.
