NOTES ON THE ORGANIZATION OF THE ROSTRAL DIENCEPHALON OF THE ATHERINOMORPH SWORDTAIL-FISH XIPHOPHORUS-HELLERI

By using conventional histological methods, the nuclear organization o f the rostral diencephalon of the swordtail-fish, Xiphophorus helleri (Poecilidae, Atherinomorpha, Teleostei) was analyzed and compared with those from other teleost species. The subdivisions of the entopeduncu lar region, especially in their relative position and cytoarchitectoni c structure, reveal clear differences between the various teleost orde rs. A new nucleus, the lateral entopeduncular nuclear area (leNA), fou nd within this region, is described.