Microscopic structure of the brain of Barbus meridionalis Risso. I. Telencephalon.

The telencephalon of Barbus meridionalis is composed of two oval telencephalic lobes separated by a medial ventricle and joined exclusively by the anterior commissure. Histologically, the dorsal and ventral telencephalic areas are well defined, the limiting plane between them being a cell free zone. In the ventral area it is possible to distinguish the following parts: dorsal, supracommissural, postcommissural, lateral, intermedia and the nucleus entopenduncularis. In the dorsal area there are three peripheral longitudinal zones--medialis, dorsalis and lateralis--together with a central zone; caudally situated is a posterior dorsolateral region which is the main receptor site for olfactory fibers and closely associated to this is the nucleus tenia. The olfactory projections to the telencephalon course along two bundles: the medial and the lateral olfactory tracts. The telencephalon projects to diencephalic regions via three large bundles: the lateral and medial telencephalic bundles and the strio-medullary system.