Skeletal Muscle EM

This is an electron micrograph of a longitudinal section of skeletal muscle. First, focus on the components in the different bands. The I-Band contains actin filaments and is bisected by the Z-disk. The A-Band contains myosin and actin filaments. The M-line is a disc-like zone where myosin filaments are crosslinked. Where are the plus and minus ends of actin filaments located? The conducting system of skeletal muscle can also be observed in this slide. Near the junction of A-and I-bands, note the T-tubules in contact with the terminal cisternae of the sarcoplasmic reticulum. Each T-tubule is in contact with two terminal cisternae at the junction, and together they form a triad. What types of ion channels are located in T-tubules and sarcoplasmic reticulum?