[Visual projections in to the brain of the sturgeon Acipenser güldenstädti]

Visual projections have been studied after unilateral lesion of the optic nerve. Degenerated fibers and terminals, as well as fibers labelled by horseradish peroxidase were found contralaterally in the lateral geniculate thalamic nucleus, the second (stratum opticum) and the third (stratum fibrosum et griseum superficiale) layers of the midbrain tectum. In other brain structures (lateral ventrothalamic nucleus, in the pretectal area--cortical nucleus, pretectal nucleus, posterior comissure nucleus) the density of degeneration of optic fibers was significantly lower. Separate fragments of degeneration were found in the fourth layer of the tectum. Ipsilaterally, thalamic, pretectal and tectal visual projections of the same localization were found, although they were less massive than at the opposite side.