Telencephalic organization in the spotted African Lungfish, Protopterus dolloi: a new cytological model

Recent studies have greatly increased our knowledge of telencephalic organization in ray-finned fishes and terrestrial vertebrates, particularly amphibians. In contrast, little new information has been generated on telencephalic organization in lobe-finned fishes. The coelacanth, Latimeria, and three genera of lungfishes constitute the living lobe-finned fishes. Latimeria is extremely rare and critically endangered, so the living lungfishes, therefore, offer the only feasible source of new information on telencephalic organization in lobe-finned fishes. A re-examination of the cytoarchitectonics of the telencephalon in the Spotted African Lungfish has allowed the generation of a new model of telencephalic organization in lungfishes. To begin to test this model, examination was made of the telencephalic distribution of acetylcholinesterase, enkephalin, the neurotensin-related hexapeptide LANT6, nitric oxide synthase (nicotinamide adenine dinucleotide phosphate-diaphorase), substance P, and tyrosine hydroxylase. This distribution supports the new model and suggests that the medial pallial-subpallial border, the striatopallidal systems, and the amygdalar organization in this lungfish are more similar to these features in terrestrial vertebrates than was previously suspected.