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Fibres: Long, multinucleated cells found in skeletal muscles; containing
approximately one thousand contracting myofibrils. They are
specialized, contracting cells that are bundled together to form muscles
Tubular organelles found in muscle fibers that appear striated under a
microscope, they are contractile fibers in muscle tissue. They are found
lying within skeletal muscle fibers that are composed of repeating
structural units called sarcomeres.
Aging of the Organs and Systems edited by Richard Aspinall
Fundamentals and Assessment Tools for Occupational Ergonomics By William S. Marras, Waldemar Karwowsk Please let me know if you need any clarification. I'm always happy to answer your questions.