Lack of sprouting and its presence after lesions of the cat spinal cord

摘要: Abstract Degeneration methods were used to study the dorsal root and descending projections after chronic partial denervation of adult cat spinal cord. Conventional mapping used, supplemented in some cases by densitometric measurements amounts degeneration present. The amount shrinkage gray matter sections was estimated planimetric measurement. Two preparations used: (1) unilateral rhizotomy which all roots caudal T4 cut except L6 (spared preparation); (2) complete deafferentation. projection examined spared preparations. T13 deafferented lowest remaining root. systems mapped displayed an increased lateral portion horn, zona intermedia. Clarke's nucleus base reticular zone gracilis. (T13) its laminae VII VIII In cases, when resulted from prior denervation, increase never exceeded boundaries normal projection. No sprouting observed those regions with strictest topographical organization, cell nests gracilis or lamina IX cord, even though these partially denervated lesions. Descending on experimental side 12 but not preparations, suggesting that presence may prevent systems. Because indicated maximal occurred segments showing least (sprouting into segment), this case cannot account for density degeneration. These results suggest certain conditions are important regulation CNS. Firstly, is limited a requirement proximity and/or overlap. Secondly, strictness localization within particular region limit likelihood region. Finally, competitive hierarchical relationship among modify capacity system sprout.