Motor unit in old age.
D000375:Aging / Q000502:physiology*; D000818:Animals; D009132:Muscles / Q000294:innervation*; D009410:Nerve Degeneration / Q000502:physiology*; D009411:Nerve Endings / Q000502:physiology*; D009416:Nerve Regeneration / Q000502:physiology*; D051381:Rats