Cerebrospinal fluid.
D000818:Animals; D001099:Arachnoid / Q000502:physiology; D002552:Cerebral Ventricles / Q000502:physiology*; D002555:Cerebrospinal Fluid / Q000502:physiology*; D002557:Cerebrospinal Fluid Shunts; D006801:Humans; D006849:Hydrocephalus / Q000601:surgery