STEVE GSCHMEISSNER / SCIENCE PHOTO LIBRARY STEVE GSCHMEISSNER / SCIENCE PHOTO LIBRARY
Skeletal muscle. Coloured scanning electron micrograph (SEM) of skeletal muscle fibres. Muscle fibres are extremely long, cylindrical cells. Running the length of each fibre are thin threads called myofibrils. The myofibrils contain the proteins actin and myosin, which slide over each other to allow the muscle to contract. These proteins give the fibres a banded appearance, and skeletal muscle is also called striated muscle due to this. It is also called voluntary muscle, as it is under direct conscious control. Magnification unknown.
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