Central projections of the lateral line and 8th nerves in the bowfin amia calva
Journal of Comparative Neurology 197(1): 1-16
ISSN/ISBN: 0021-9967 Accession: 004898947
The 1st-order connections of the anterior and posterior lateral line nerves and of the 8th nerve were determined in the bowfin, A. calva, using experimental degeneration and anterograde HRP [horseradish peroxidase] transport techniques. The termination sites of these nerves define a dorsal lateralis cell column and a ventral octavus cell column. The anterior and posterior lateralis nerves distribute ipsilaterally to 2 medullary nuclei-nucleus medialis and nucleus caudalis. Nucleus medialis comprises the rostral 2/3 of the lateralis column and contains large, Purkinje-like cells dorsally and polygonal, granule and fusiform cells ventrally. Nucleus caudalis is located posterior to nucleus medialis and consists of small, granule cells. Anterior lateralis fibers terminate ventrally to ventromedially in both nucleus medialis and nucleus caudalis. Posterior lateralis fibers terminate dorsally to dorsolaterally within these 2 nuclei. A sparse anterior lateralis input may also be present on the the dendrites of 1 of the nuclei within the octavus cell column, nucleus magnocellularis. The anterior and posterior rami of the 8th nerve each terminate within 4 medullary nuclei which comprise the octavus cell column: the anterior, magnocellular, descending and posterior octavus nuclei. An 8th nerve projection to the medial reticular formation is also present. Some fibers of the lateralis and 8th nerves terminate within the ipsilateral eminentia granularis of the cerebellum. Lateralis fibers distribute to approximately the lateral half of this structure with posterior lateral line fibers terminating laterally and anterior lateral line fibers terminating medially. Eighth nerve fibers distribute to the medial half of the eminentia granularis.