The Nikon MicroscopyU confocal microscopy image gallery was created with a PCM-2000 confocal scanning system interfaced to a Nikon Eclipse E600 upright microscope. Images were recorded in successive z-axis serial sections with C-Imaging Systems software with excitation illumination provided by an argon-ion and/or a helium-neon laser.

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Charles Darwin established a relevant truth when he claimed, "function alters structure". When the workings of the primate skeletal muscle are closely examined at the tissue, cellular, and subcellular level, his statement rings even clearer in the case of malfunctions such as muscular dystrophy. This crippling genetic disorder causes the progressive wasting and weakening of the voluntary muscles (such as the biceps of the arm) on the exterior of the body. Unlike polio, the internal muscles such as the diaphragm, are not affected by muscular dystrophy.

Muscles are tissues composed of bundles of fibers (fascicles) having varying lengths and diameters that can shorten, thicken, or lengthen depending on the location and the message sent by the controlling neurons. The change in the muscle fibers allows for the movement of body parts, whether it is involuntary (e.g., breathing by moving the lungs and blood circulation by the pumping of the heart) or voluntary where the primate can exert control (e.g., arm and leg muscles). The skeletal muscle is surrounded by a layer of connective tissue. Skeletal muscles, characteristically striated, attach to the bones by tendons that are strong, fibrous, non-elastic cords. The contraction or extension of the skeletal muscles causes the attached bones forming joints to move either by flexing or extending. Humans, one type of primate, have more than 600 muscles, accounting for approximately 40 percent of the average male's weight.

Skeletal muscle cells are multinucleated with the nuclei on the periphery of the cell. Acetycholine is the excitatory neurotransmitter that is released from the fine branches of the motor neuron that contact the muscle cell.

Modern medical and genetic research uses the nonhuman primate skeletal muscle as a living model of human tissue. Recent research suggests that skeletal muscle tissue contains populations of satellite cells (a type of stem cell) that when triggered by a cellular substance (mitogen), re-enter the cell cycle and proliferate upon muscle injury, forming new muscle or myofibers.