THE ZEBRAFISH BRAIN - A NEUROANATOMICAL COMPARISON WITH THE GOLDFISH

The zebrafish Danio rerio is an important model system for genetic and developmental studies of the vertebrate central nervous system. Consi derable knowledge concerning the embryonic development of the central nervous system of the zebrafish has accumulated in recent years. Howev er, there is an apparent lack of information on the organization of th e adult zebrafish brain. We have therefore recently studied in detail the neuroanatomy of the adult zebrafish, Here we compare the brains of the zebrafish and of the closely related and neurobiologically well-i nvestigated goldfish, Carassius auratus. Two sensory systems, the visu al and the gustatory systems, were identified as differing on the gros s morphological and histological levels in the two species. The goldfi sh shows the simple (evolutionarily reduced) pattern of prerectal orga nization, and its gustatory system is massively enlarged. The pretectu m of the zebrafish conforms to this simplified visual prerectal patter n, although the retention of some ancestral prerectal characters indic ates a lesser degree of reduction of the visual system compared to the goldfish. The gustatory system shows many similarities with the evolu tionarily derived and functionally specialized gustatory system of the goldfish. However, some peripheral and central gustatory characters a re missing in the zebrafish, indicating a less specialized gustatory s ystem.