Effect of glial-ependymal scar and Teflon arrest on the regenerative capacity of goldfish spinal cord

The regenerative capacity of the goldfish spinal cord is not affected by connective tissue or parenchymal scars in the normal course of regeneration. The present experiments were undertaken to study the effects of both mechanical arrest and a glialependymal scar blockade on the regenerative capacity of the spinal cord. Spinal cords of fifty goldfish were transected and Teflon was placed between the severed stumps. Fourteen, 30, 60, or 90 days later, the Teflon was removed and regeneration assessed up to 6 months postoperatively. Regeneration of the spinal cord was severely retarded after 14 days of Teflon arrest and did not occur after 30 or more days of arrest. After abortive regeneration, nerve fibers were found to terminate at a glial-ependymal scar. To ascertain if the loss in regenerative capacity was due to the glial-ependymal scar or Teflon arrest, the spinal cord was cut and Teflon inserted for 30 days. The Teflon was then removed and the cord transected one segment rostral to the former mechanical block. Thirty days later the axons had regenerated through the isolated spinal cord segment and past the glial-ependymal scar. Therefore, the inability of the axons to regenerate after Teflon removal was due to the inability of the neurons to resume growth and not to any mechanical effects of the scar.