[Architecture of the pathways and primary optical centers in trout (Salmo irideus Gibb.)]

The retinal projections of the Trout were examined on fifteen adult specimens (eighteen months) unilaterally enucleated. After a post-operative survival period of six to 31 days, the degenerating fibers were stained with Fink-Heimer technique. The optic tract is entirely crossed. At the rostral end of the thalamus a first fascicle diverges which runs to aventral thalamic center and to a dorsal thalamic center. The latter extends caudally as a pretectal center. The second fascicle is a retinogeniculo-tectal pathway which borders the geniculate body and enters the external tectal layer. The corpus geniculatum is large, well laminated and contains terminal degeneration. The main part of the optic tract includes three fascicles. Each of them sends fibers to all three tectal layers.