Sarcoplasmic reticulum resembles endoplasmic reticulum found in other cells; they are structures that surround the myofibrils of skeletal muscle fibers. T tubules or transverse tubules run perpendicular to the axis of the fiber and extend across the surface of sarcoplasmic reticulum. It's role is to conduct impulses from sarcolemma to cell and to sarcoplasmic reticulum.