The tubule system in these cephalocarid muscles consists of the transverse tubules (t-tubules), which invaginate from the sarcolemma at the level of the 1-band and Z-line, with branches in the A-band region forming part of a triad (Fig.
Muscle fibers in the onycophoran Peripatus dominicae are not subdivided into myofibrils, although the fiber is populated with many tubule systems, including sarcoplasmic reticulum and t-tubules (Hoyle and Williams, 1980).
Likewise, mice fed a HFD become obese, develop IR, and display increased levels of cholesterol in isolated skeletal muscle T-tubule membranes and adult muscle fibers .
The T-tubule system of skeletal muscle is an intricate network composed of narrow tubules of around 40-85 nm in diameter which originate from deep invaginations of the surface plasma membrane .
T-Tubule Cholesterol Levels Influence the EC Coupling Process
During muscle contraction, the action potential elicited at the neuromuscular junction propagates through the surface membrane into the T-tubule network, which is a key element in the EC coupling process .