Intraspinal Sprouting of Dorsal Root Axons

Introduction The considerable ability of the central nervous system to adapt functionally and to compensate for a loss of neuronal tissue is well established. Several hypotheses have been presented to explain the nature of this functional recovery. Although no critical evidence has been obtained, it can be stated for the mammal, with only a few observations to the contrary (Sugar and Gerard21and Freeman6), that regeneration of severed axons is not the responsible mechanism. The failure of severed axons to regenerate in the central nervous system does not necessarily exclude a morphological basis for the compensation, for Cajal19has mentioned several instances in which traumatic injury to the spinal cord and brain resulted in formation of new processes from nerve cells in the injured area. Further support for such a contention comes from the recent observations that partially denervated skin and muscle can be effectively reinnervated not