ISSN:
1432-0568
Keywords:
Brainstem
;
Mechanosensory system
;
Otavolateral efferents
;
Teleost
;
Tract-tracing
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The efferent neurons of the lateral line system of the euteleost Aplocheilus lineatus and the osteoglossomorph Pantodon buchholzi, both surface feeding fish, were examined by neuronal tract tracing. Besides horseradish peroxidase, fluorescent dextrans were used as tracers to allow simultaneus visualization of projections from different lateral line branches. Labeled efferent neurons were found in nuclei situated in the medulla ventral of ventricle IV. This position resembles the octavolateralis efferent nucleus of previous studies. The number of labeled cells in the efferent nucleus is low in both species. Most neurons were found ipsilaterally to the application site, some along the midline and only very few contralaterally. The size of efferent cells differs distinctly between Aplocheilus, possessing small cellbodies (length 16.5 μm), and Pantodon, which has very large efferent cells (length 47.0 μm). Efferent axon bundles course rostrally in both species, leaving the brain at the level of the anterior lateral line nerve. Only Aplocheilus has in addition lateral axon bundles leaving the brain at the level of the posterior lateral line nerve. After application of one fluorescent tracer to the lateral ramus and a different fluorescent tracer to the superficial ophtalmic ramus in a given animal, double-labeling of efferent cells hardly ever occurs. If the neuromasts I and IV of the dorsal skull of Pantodon are applied with one fluorescent tracer each, ∼10% of centrally labeled cells are double-labeled. Considering the results of double-labeling, the concept of a differential innervation of lateral line branches is supported and discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00187138
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