Anatomical evidence for the influence of degenerating pathways on regenerating optic fibers following surgical manipulations in the visual system of the goldfish

We have used ³H]proline radioautography to trace regenerating optic fibers in the goldfish following: (1) the removal of the right tectal lobe and the right eye, and (2) the removal of both tectal lobes. Our results indicate that following the removal of the right tectal lobe and the right eye, both the denervated tectal efferent pathways, and the denervated visual pathways and terminal zones of the enucleated eye were penetrated by the regenerating optic fibers. In addition, following bilateral lobectomy, the denervated tectal efferent pathways were bilaterally penetrated by the regenerating fibers. Since, in both types of operations, these denervated pathways and terminal zones should undergo degeneration, our results support the suggestion that the presence of degenerating axonal debris and proliferating glia may play an important role in guiding regenerating optic fibers in the visual system of the goldfish.