• olfaction;
  • olfactory tracts;
  • lateral palium;
  • elasmobranches;
  • telencephalon


The secondary olfactory connections in the shark Scyliorhinus canicula and the ray Raja clavata have been studied with reduced silver techniques. After transction through the pedunculus olfactorus in Scyliorhinus degenerating fibers could be traced to the telencephalic hemisphere. On entering the henisphere these fibres subdivide into a small medial and a larger lateral olfactory tract. The medical olfactory tract also projects contralaterally to the submeningeal pallial zone via the commissural olfactoria inferior and to the stratum granulare bulbi olfactorii by way of the commissural olfactoria superio. The lateral olfactory tract distrubytes mainly to the pallium laterale. A striking difference between Scyliorhibnus and Raja is that in the latter no contralaterature for other cartilaginous fishes, it appears that the secondary olfactory connections of Sycliorhinus are more extensive than in other chondrichthians studied experimentally.

In some cases of peduncle transction in Scyliorhinus the lateral part of the sttiatum was also involved in the lesion. In addition to the pattern of degeneration seen after olfactory peduncle lesions, degenerating fibres could be distinguished both in the stria medullaris and basal forebrain bundle. The former projects to hebenular nucleus, whereas the latter distributes to the hypothalamus, and brainstem tegmentum.