Wallerian DegenerationNicotinamide-Nucleotide AdenylyltransferaseSciatic NerveNerve DegenerationAxonsAxotomyMyelin SheathSciatic NeuropathySchwann CellsInfarction, Anterior Cerebral ArteryNerve CrushNerve RegenerationPeripheral NervesPyramidal TractsOptic NervePeripheral Nerve InjuriesTrauma, Nervous SystemElectrophysiological ProcessesMice, Neurologic MutantsRetinal DegenerationNeurofilament ProteinsMacular DegenerationNerve Fibers, MyelinatedSpinal Nerve RootsNerve Tissue ProteinsDiffusion Magnetic Resonance ImagingGanglia, SpinalPeripheral Nervous SystemMice, Inbred C57BLDemyelinating DiseasesMotor NeuronsSpinal Cord Injuries