Circumventricular Mesencephalic Trigeminal Midline Ridge Formation in Cartilaginous Fishes: Species Variations

MacDonnell, Malcolm F.

doi:10.1159/000121310

Cited by 7 publications

(1 citation statement)

References 6 publications

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“…These compo nents are brought together in an anatomically distinct region of the ependymal wall of the tectum that has previously been designated the midline ridge forma tion (MRF) of the Mes V system [18,19].…”

Section: Introductionmentioning

confidence: 99%

Sub/Supraependymal Axonal Net in the Brains of Sharks and Probable Targets in Parasynaptic Relationship

MacDonnell

1989

Brain Behav Evol

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A sub/supraependymal system of varicose axons in the tectal midline ridge formation of shark brains is described. Lengths of axons and their terminals are seen freestanding in the cerebrospinal fluid (CSF) as well as in close contiguity with the large CSF-contacting and supraependymal mesencephalic trigeminal neurons of the midline ridge formation. The relationship of axonal varicosities and terminals to both CSF and supraependymal somata is such as to suggest a nonsynaptic association. This finding is discussed in the context of its utility in testing the concept of parasynaptic modulation in vertebrate brains. The topographical arrangement described is one in which the essential operational elements of parasynaptic activity can be identified in a neuronal assemblage whose functional association is known.

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Section: Introductionmentioning

confidence: 99%

Sub/Supraependymal Axonal Net in the Brains of Sharks and Probable Targets in Parasynaptic Relationship

MacDonnell

1989

Brain Behav Evol

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HRP study of the central components of the trigeminal nerve in the larval sea lamprey: Organization and homology of the primary medullary and spinal nucleus of the trigeminus

Anadón

Miguel

Gonzalez‐Fuentes

et al. 1989

J of Comparative Neurology

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The medullary and spinal connections of the trigeminal nerve of larval sea lampreys Petromyzon marinus were studied by anterograde and retrograde HRP transport after application into the orbit. Three components were found, all of them ipsilateral: 1) The motor nucleus was undivided in the larva, and its neurons possessed a rich dendritic tree. The single motor root was well separated from the sensory root. 2) The descending root was laterally located, and its fibers ran compactly to spinal levels. 3) Most medullary and many rostral spinal dorsal cells were labeled. Dorsal cells, which were mostly multipolar, had numerous mutual contacts. Some dorsal cell processes contacted the fourth ventricle. The name "primary medullary and spinal nucleus of the trigeminal nerve" (PMSV) is proposed for these dorsal cells. Medullary dorsal cells were not labeled by applying HRP at the level of spinal nerves, but application to the vagus nerve did label some. The possible relationship of this nucleus with the mesencephalic trigeminal nucleus of jawed vertebrates is discussed.

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Cartilaginous Fishes

Smeets¹

1998

The Central Nervous System of Vertebrates

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Circumventricular Mesencephalic Trigeminal Midline Ridge Formation in Cartilaginous Fishes: Species Variations

Cited by 7 publications

References 6 publications

Sub/Supraependymal Axonal Net in the Brains of Sharks and Probable Targets in Parasynaptic Relationship

Sub/Supraependymal Axonal Net in the Brains of Sharks and Probable Targets in Parasynaptic Relationship

HRP study of the central components of the trigeminal nerve in the larval sea lamprey: Organization and homology of the primary medullary and spinal nucleus of the trigeminus

Cartilaginous Fishes

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