Dorsal root implant on lesioned spinal cord morphologic findings of regeneration of synapses in the mammalian spinal cord--repair and recovery.

Earlier work concerning regeneration of synaptic connection had been studied primarily in amphibia. Sperry and Miner and Stevens showed that functional regeneration of synapses followed sectioning and anastomosis of the central process of the dorsal root of one side to the proximal stump of the dorsal root of the opposite. A number of studies have shown that the dorsal roots and dorsal columns of mammals have adequate regenerative capacities. There is no functional or morphologic evidence for reestablishment of synaptic connections reported in the mammalian studies. A number of authors have reported that regenerating dorsal root fibers are confronted with a barrier at the neutilemmal-glial junctions. Previous studies have shown that peripheral nerve fibers inserted into the spinal cord grow profusely. Theorizing that regenerating dorsal root fibers would grow and reestablish synaptic connection more readily, it was decided to insert the neurilemmal portion- including Schwann cells- of the dorsal roots into the spinal cord to the depths of the gray columns.