A structural study of the optic nerve of Hydromantes genei

The structure of the optic nerve of Hydromantes genei, was investigated by confocal laser scanning microscopy and by the Cajal-De Castro method. This nerve appears to be composed of unmyelinated fibres, which is a rare case i n amphibians. In view of this and the fact that it contains a relatively sm all number of nervous fibres, the optic nerve of N. genei, in comparison wi th other species of Plethodontidae, can be considered a structure with a lo w level of complication.