Immunocytochemical Evidence for Electrical Synapses in the Dorsal Descending and Dorsal Anterior Octaval Nuclei in the Goldfish, Carassius auratus

The dorsal portion of the descending octaval nucleus (dDO), the main first-order auditory nucleus in jawed fish, includes four lateral and three medial neuronal populations that project to the auditory midbrain. One medial population and one lateral population contain neurons that receive a remarkably large axon terminal from the utricular branch of the octaval nerve. Immunocytochemistry for connexin 35 (Cx35) was used to determine whether this connection includes electrical synapses. Although Cx35 was not localized to these large contacts, it was observed in the three other lateral dDO populations. Another first-order nucleus, the dorsal portion of the anterior octaval nucleus (dAO), primitively projects to the auditory midbrain in jawed fishes and contains neurons positive for Cx35. Utricular branch terminals were coincident with some Cx35 puncta in dDO and dAO. The results are discussed in light of what is known about the occurrence of electrical synapses in first-order auditory and vestibular nuclei in fish and tetrapods.

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Mechanosensory Lateral Line Nerve Projections to Auditory Neurons in the Dorsal Descending Octaval Nucleus in the Goldfish, Carassius auratus

Brain Behavior and Evolution ◽

10.1159/000447943 ◽

2016 ◽

Vol 88 (1) ◽

pp. 68-80 ◽

Cited By ~ 3

Author(s):

Catherine A. McCormick ◽

Shannon Gallagher ◽

Evan Cantu-Hertzler ◽

Scarlet Woodrick

Keyword(s):

Lateral Line ◽

Low Frequency ◽

Cell Types ◽

Auditory Pathway ◽

Projection Neurons ◽

Specific Cell ◽

Lateral Line Nerve ◽

First Order ◽

Goldfish Carassius Auratus ◽

Auditory Nucleus

The nucleus medialis is the main first-order target of the mechanosensory lateral line (LL) system. This report definitively demonstrates that mechanosensory LL inputs also terminate in the ipsilateral dorsal portion of the descending octaval nucleus (dDO) in the goldfish. The dDO, which is the main first-order auditory nucleus in bony fishes, includes neurons that receive direct input from the otolithic end organs of the inner ear and project to the auditory midbrain. There are two groups of such auditory projection neurons: medial and lateral. The medial and the lateral groups in turn contain several neuronal populations, each of which includes one or more morphological cell types. In goldfish, the exclusively mechanosensory anterior and posterior LL nerves terminate only on specific cell types of auditory projection neurons in the lateral dDO group. Single neurons in the lateral dDO group may receive input from both anterior and posterior LL nerves. It is possible that some of the lateral dDO neurons that receive LL input also receive input from one or more of the otolithic end organs. These results are consistent with functional studies demonstrating low frequency acoustic sensitivity of the mechanosensory LL in teleosts, and they reveal that the anatomical substrate for sensory integration of otolithic and LL inputs is present at the origin of the central ascending auditory pathway in an otophysine fish.

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SEM of Hepatocytes and Biliary Passages in Goldfish Liver

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100080213 ◽

1977 ◽

Vol 35 ◽

pp. 556-557

Author(s):

Waykin Nopanitaya ◽

Joe W. Grisham ◽

Johnny L. Carson

Keyword(s):

Carassius Auratus ◽

Cell Layer ◽

Three Dimensional ◽

Cell Types ◽

Biliary System ◽

Fish Food ◽

Commercial Fish ◽

Goldfish Carassius Auratus ◽

Commercial Fish Food

An interesting feature of the goldfish liver is the morphology of the hepatic plate, which is always formed by a two-cell layer of hepatocytes. Hepatic plates of the goldfish liver contain an infrequently seen second type of cell, in the centers of plates between two hepatocytes. A TEH study by Yamamoto (1) demonstrated ultrastructural differences between hepatocytes and centrally located cells in hepatic plates; the latter were classified as ductule cells of the biliary system. None of the previous studies clearly showed a three-dimensional organization of the two cell types described. In the present investigation we utilize SEM to elucidate the arrangement of hepatocytes and bile ductular cells in intralobular plates of goldfish liver.Livers from young goldfish (Carassius auratus), about 6-10 cm, fed commercial fish food were used for this study. Hepatic samples were fixed in 4% buffered paraformaldehyde, cut into pieces, fractured, osmicated, CPD, mounted Au-Pd coated, and viewed by SEM at 17-20 kV. Our observations were confined to the ultrastructure of biliary passages within intralobular plates, ductule cells, and hepatocytes.

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