fibril(redirected from muscle fibril)
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a filamentous structure found in the cells and tissues of animals and plants. Fibrils include formations of various origin and functional significance. They may be examined with a light microscope (for example, collagen and elastic fibers, myofibrils, and tonofibrils) or an electron microscope (for example, the protofibrils of muscles and cytoplasmic microfibrils).