transverse tubules

Updated About encyclopedia.com content Print Article Share Article
views updated

transverse tubules (T tubules) A series of infoldings of the plasma membrane (sarcolemma) of muscle fibres that envelop each myofibril at the Z line (see sarcomere). The T tubules transfer action potentials from the sarcolemma to the sarcoplasmic reticulum, which releases calcium ions into the cytosol causing contraction of the muscle fibres.