CYTOARCHITECTURE OF THE MEDIAL OCTAVOLATERALIS NUCLEUS IN THE GOLDFISH, CARASSIUS-AURATUS

The medial octavolateralis nucleus (MON) is the principal first-order medullary lateral line sensory nucleus found in the majority of anamni otic vertebrates. Although its presence has been confirmed in numerous taxa, the cytoarchitecture of this region has not been extensively st udied in any species. The purpose of this study was to examine in deta il the cytoarchitecture of the MON in the goldfish using Golgi stainin g and HRP histochemical techniques. The results of this study demonstr ated the presence of a number of cell types with distinct cellular mor phologies, several of which strongly resemble those described in octav olateralis nuclei dedicated to audition and electroreception. The most prominent of these MON neurons included crest cells of two varieties, either possessing or lacking basilar dendrites. Additionally, we desc ribed stellate and cristal interneurons and granule-like cells in the molecular layer, and lateral interneurons and granule-like neurons in deeper MON layers. These morphological similarities together with simi larities in functional organization, and the probable close phyletic r elationships of this ''family'' of hair cell sensory systems, argue fo r parallels in mechanisms of sensory processing and analysis in strong ly divergent sensory modalities. (C) 1996 Wiley-Liss, Inc.