I-band

The I-band is a specific region within a muscle fiber, recognized in muscle microscopy and anatomy. It contains only thin (actin) filaments and serves as a connective zone between adjacent dark bands called A-bands. When muscles contract, the I-band shortens as the actin filaments slide over the thick (myosin) filaments, which stay stationary. The I-band appears lighter under a microscope, helping scientists understand muscle structure and how muscles work during movement. Its precise organization is essential for proper muscle function.