Aberrant axonal paths in regenerated goldfish retina and tectum opticum following intraocular injection of ouabain.

Following ouabain-induced degeneration, the neural retina and the retinotectal axons regenerate. The pathways of regenerated retinal ganglion cell axons in retina and in tectum are visualized by labeling with horseradish peroxidase (HRP) applied to the optic nerve. In retina, the axons exhibit highly abnormal courses, including extensive fascicle crossing, hairpin loops and circular routes. In tectum, retinal axon fascicles are not neatly aligned in a normal fascicle fan. Instead, long and short fascicles are mixed, and take erratic routes, crossing each other and crossing the tectal equator.