Neuronal connections through the posterior commissure in the frog Rana esculenta.

The cobalt-labelling technique was used. After iontophoretic injections of cobaltic-lysine complex into the posterior commissure, fibres and neurons were bilaterally labelled in the posterior thalamic nucleus, three other pretectal nuclei, the optic tectum, the nucleus of the medial longitudinal fasciculus, and in the basal optic nucleus. Unilateral cobalt injections into the terminal areas of the posterior commissure in the mesencephalic tegmentum, labelled neurons in the above-mentioned nuclei ipsilaterally, and some cells contralaterally. The connections through the frog's posterior commissure are very similar to those in mammals.