MAIN HISTOLOGICAL FEATURES OF THE MUSCLE FIBERS
Skeletal muscle fibers
They are shaped as long cylinders that can be as long as the muscle to which they belong. They are multinucleated, and their many nuclei are placed at the periphery of the fiber, under the plasma membrane. Observed with a microscope they show characteristic transverse bands in their cytoplasm, and for this reason this type of muscle is called striated muscle.
They are shaped as long cylinders that can be as long as the muscle to which they belong. They are multinucleated, and their many nuclei are placed at the periphery of the fiber, under the plasma membrane. Observed with a microscope they show characteristic transverse bands in their cytoplasm, and for this reason this type of muscle is called striated muscle.
Cardiac muscle fibers
Their form is of short cylinders that have one or two nuclei in the center of the cell. Their cytoplasm shows transverse bands (it is striated), similarly to that of skeletal muscle. The fibers adhere to each other at their ends by intercellular junctions. Each group of junctions (shown in the diagram by dark lines) is called an intercalated disc. These discs are also called scalariform discs because they often resemble the steps of a ladder.
Smooth muscle fibers
They are spindle-shaped and their nucleus is central. Because their cytoplasm does not show transverse striation they are called smooth muscle fibers.
