muscle fibers contract the muscles when stimulated.
Yes, muscles are made up of muscle fibers. If you want to know more about muscles go to this site: http://kidshealth.org/teen/your_body/body_basics/bones_muscles_joints.html#
i think it is lack mitochondria.... but it could also be lack a plasma membrane and have many nuclei.
To contarct and release, thereby giving movement to the body.
'Muscle fiber' means an elongated contractile cell that forms the muscles of the body