Long-term degeneration renders central tracts refractory to penetration by regenerating optic fibers.
We have examined time-dependent changes in the ability of degenerating central pathways in the goldfish to be penetrated by regenerative axons. We have found that when a tract has degenerated for 2--5 weeks it is readily penetrated by regenerating optic fibers. However, tracts which degenerated for any longer than 6 weeks, before being exposed to the regenerating fibers, were only sparsely penetrated by them. We conclude that over a period of no less than 6 weeks, degenerating central tracts in the goldfish change their character and become relatively refractory to penetration by regenerating axons.
D000818:Animals; D001369:Axons / Q000502:physiology; D006054:Goldfish; D009410:Nerve Degeneration; D009416:Nerve Regeneration; D009799:Ocular Physiological Phenomena; D009900:Optic Nerve / Q000502:physiology*