Peripheral configuration and central projections of the lateral line system in Astronotus ocellatus (cichlidae): A nonelectroreceptive teleost

Abstract

The lateral line system of Astronotus ocellatus comprises one trunk canal, one tail canal, and three head canals. The sensory receptors on the head are innervated by rami of the dorsal anterior, ventral anterior, and posterior lateral line nerves, and those along the trunk and tail by rami of the posterior lateral line nerve. The peripheral configuration of lateral line canals and nerves was examined in whole mount preparations, the central connections of restricted groups of endorgans studied using HRP and degeneration methods, and the neuronal morphology and cytoarchitecture of the lateralis region investigated with Nissl, silver, and Golgi methods. Neurons of the lateralis cell column are diffusely arrayed and of variable morphology. They are oriented primarily in the transverse plane and, with the exception of a dorsal lamina of large multipolar cells, are not organized into zones. Lateralis fibers bifurcate on entering the brainstem, course in lateral tracts, and give off medially directed collaterals to terminate in the ipsilateral nucleus medialis and nucleus caudalis. In addition, fibers terminate in the eminentia granularis of the cerebellum, but only fibers supplying endorgans in the head canals penetrate the granule cell zone of the cerebellar corpus. Fibers supplying sense organs in adjacent canals overlap in their central endings, whereas fibers of distantly separated receptors do not overlap. The rami supplying trunk and tail canal organs do not project as far rostrally in the central neuropil as do the other rami. Endings of posterior lateral line fibers lie dorsal to those of the anterior lateral line nerves, and some lateralis fibers terminate within the confines of the magnocellular, descending, and posterior nuclei of the octavus column. Although there is spatial order to the lateralis projections, there is no clear somatotopic organization in the lateralis region.

Neural Pathway for Aggressive Display in <i>Betta splendens: </i>Midbrain and Hindbrain Control of Gill-Cover Erection Behavior

“…2b). The location of nucleus me dialis in Betta is similar to that described in the cichlid Astronotus ocellatus [Meredith, 1984], except that the nucleus extends further medially in Betta, reaching the ventricle (see fig. lb-d).…”

“…HRP was visualized by using letramethylbcnzidinehcptamolybdatc [Olucha cl al., 1985), and cells were counlcrstaincd with neutral red. HRP-labelcd cells and processes were identified based on the neuroanatomical descriptions of Ariens-Kappers et al [1936], Luitcn [1976], McCormick [1983], Meredith and Butler [1983], Meredith [1984] and Niuwenhuys and Pouwcls [1983]. The anatomy of the motor nuclei of cranial nerves V, VII and IX-X in Bella has been described by Gorlick [1989],…”

Primary Connections of the Anterior and Posterior Lateral Line Nerves in the Oyster Toadfish

“…Lateralis projections to the cerebel lum appear to be somewhat variable in teleosts [Claas and Munz, 1981;Zottoli and Van Horne, 1983;Mere dith, 1984;Metcalf et al, 1985]. Interestingly, in Asironoius only anterior lateral line nerves project to the corpus cerebelli [Meredith, 1984], In nonelectric actinopterygian fishes, octaval pro jections are largely separate from lateralis ones [McCormick, 1982;Boord and McCormick, 1984]; however, nucleus magnocellularis typically receives projections from both systems. In the toadfish both lateralis nerves project to nucleus magnocellularis but not to other octaval nuclei.…”

“…The euteleosts include three ostariophysians -the goldfish Carassius auraius [Puzdrowski, 1983;Zottoli and Van Horne, 1983], the zebrafish Brachydanio rerio [Metcalf et al, 1985] and the blind cave characin Astyanax hubbsi [Voneida et al, 1983], and three acanthopterygians -the black molly, Mollensia sphenops [Claas and Munz, 1981] and two cichlids, Crenicichla lepidota [McCormick, 1983] and Astronotus ocellatus [Meredith, 1984]. This study of a toadfish (family Batrachoididae) is the first to report experi mental neuroanatomical data on a member of the su perorder Paracanthopterygii.…”

Sonic Motor Nucleus and Its Connections with Octaval and Lateral Line Nuclei of the Medulla in a Rockfish, <i>Sebastiscus marmoratus</i>

“…Several authors have proposed the existence of five octaval nuclei and two lateral line nuclei in the medulla of teleost fishes, as the first-order relay nuclei [McCormick, 1983[McCormick, , 1992Meredith and Butler, 1983;Finger and Tong, 1984;Meredith, 1984;Puzdrowski, 1989;Highstein et al, 1992;McCormick and Braford, 1993;McCormick and Hernandez, 1996]. It is known that there are seven endorgans of the inner ear in bony fishes: the three otolithic endorgans (saccule, lagena, and utricle), the macula neglecta, and the three semicircular canals [Fay and Popper, 1980;Meredith and Butler, 1983;Schellart and Popper, 1992].…”