Wallerian degeneration in the optic nerve of a reptile: An electron microscopic study


  • Supported by USPHS Grants NB-04578 and NB-06594.


Numerous optic nerve fibers persist for a period of up to 20 months following enucleation in reptiles, although it is unlikely that a significant number of efferent fibers are present. After varying survival periods, almost all nerve fibers display distinct morphological changes probably associated with degeneration, but most features previously associated with early stages of degeneration can be seen in long-survival material except for the early and rapid loss of all non-myelinated fibers and a honeycomb tubular degeneration associated with the inner and outer myelin layers. Distinct sequential stages of axon and myelin degeneration could not be ascertained despite the slow rate of degeneration in poikilotherms. The varieties of abnormal axon morphology are documented and considered in terms of current light microscopic staining methods.