Uncrossed retino-geniculate and retino-tectal projections in the hereditary unilaterally microphthalmic rats.

The dorsal lateral geniculate nucleus (CGLd) of the hereditary unilaterally microphthalmic rats showed a diminution of volume and an increase of neuronal density on the contralateral side of the vestigial eye without the optic nerve (about 60 and 160% of the normal, respectively; P less than 0.001). No significant changes were observed in the ipsilateral CGLd. Uncrossed retino-CGLd and -tectal projections were studied using the anterograde axonal transport of HRP in adult rats with the congenital unilateral microphthalmia. Aberrant expansions of the uncrossed retinal projection widely covered CGLd and the superficial layers of the superior colliculus (SCS). The distribution pattern of expanded uncrossed retinal pathway in the mutant was essentially similar to that of neonatally one-eyed rats.