Most groups of skeletal muscle fibers of the body are organized into bundles of different complexity.
There is usually a small amount of loose connective tissue between the muscle fibers. This connective tissue is important because it contains the blood vessels, lymphatic vessels, and nerves that nourish and innervate the fibers. This tissue is called endomysium (in red in the drawing and highlighted in the same color in the image of the histological section).
A greater quantity of dense connective tissue gathers groups of skeletal muscle fibers into bundles called fascicles. This dense connective tissue is called perimysium (in green in the drawing and highlighted in the section).
The muscle as a whole is surrounded by a layer of dense, regular connective tissue called the epimysium. This layer surrounds all of the muscle’s fascicles (in pink in the drawing).
The lower image is a cross-section of skeletal muscle stained with a trichrome dye, which is very useful for differentiating and highlighting connective tissue (perimysium in green, endomysium in red).
Skeletal muscle. Staining: Masson’s trichrome. Magnification: small.
