Ultrastructural identification of degenerating boutons of monosynaptic pathways to the lumbosacral segments in the cat after spinal hemisection.

摘要: Electrophysiological results suggest that the supra-spinal monosynaptic pathways to lumbosacral motoneurones in cats are located vestibulospinal and reticulospinal tracts. In present study these were interrupted upper thoracic region by hemisection of spinal cord. The boutons undergoing degeneration then studied both qualitatively quantitatively means serial single sections selected areas ventral horn cord segments L 6, 7 S 1. degenerating distributed over cell soma larger dendrites (but not most proximal portions) motoneurones. Two days postoperatively showing signs readily identified latero-ventral motoneurone nucleus Rexed's lamina VIII. These which swollen had a greatly increased number neurofilaments decreased synaptic vesicles. Five now shrunken, contained mitochondria dense, granular material. Between 5 8 post-operatively invaded glial processes digested. A small percentage F- S-type (approximately 0.5 3.0% respectively) as forming terminals experimentally pathways. This did exclude possibility proportion propriospinal, fibers derived from cervical