Long-term persistence, after eye-removal, of unmyelinated fibres in the frog visual pathway.

Long-term fibre degeneration was studied in the optic nerve, and the optic tectum in Rana esculenta using the cobalt filling technique. Myelinated retinal fibres disappeared within 26 days. A number of unmyelinated axons, however, persisted during the experimental period (91 days after eye removal). It was concluded that myelinated fibres degenerate considerably faster than unmyelinated ones in the frog visual system.