A cross-section of skeletal muscle in this light micrograph shows the individual, parallel muscle fibers (red). These fibers work in concert to power movement. Thomas Deerinck, NCMIR/ScienceSource hide caption

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Experimental Technique Coaxes Muscles Destroyed By War To Regrow
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Dennis Aabo Sorensen tests a prosthetic arm with sensory feedback in a laboratory in Rome in March 2013. Patrizia Tocci/Lifehand 2 hide caption

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An Artificial Arm Gives One Man The Chance To Feel Again
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Larry Bonassar shows off an ear that he and his colleagues at Cornell University built out of living cartilage cells with the help of a 3-D printer. Lindsay France/Cornell University Photography hide caption

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