Title

The neuronal system of the saccus vasculosus of trout (Salmo trutta fario and Oncorhynchus mykiss): an immunocytochemical and nerve tracing study.

Document Type

Article

Abstract

The neuronal system of the saccus vasculosus of two species of trout was studied with immunocytochemical methods and carboindocyanine-dye (DiI) tract-tracing. The cerebrospinal-fluid-contacting neurons of the saccus were immunoreactive for gamma-aminobutyric acid (GABA), glutamic acid decarboxylase (GAD), and neuropeptide Y (NPY). Immunostaining of alternate sections of the saccus vasculosus of fry with anti-GAD and anti-NPY indicated that these substances were colocalized. The tractus sacci vasculosi and the neuropil of the nucleus sacci vasculosi were also immunoreactive to these substances. The GABA, GAD, and neuropeptide Y immunoreactivity of the saccus vasculosus system appeared early in trout ontogeny. After applying DiI to various levels of the tractus sacci vasculosi of adult trout, we observed massive bilateral saccular projections to the nucleus sacci vasculosi and could follow the course of the sacco-thalamic tract. This tract extended in the subependymal region of the thalamus rostral to the nucleus sacci vasculosi and split into two small tracts that reached the subhabenular-preoptic region. Sacco-thalamic fibers formed extensive periependymal plexuses along their trajectory. Interestingly, no clear evidence of the existence of a saccopetal system was obtained. On the basis of these results, we postulate that the saccus vasculosus system modulates the function of centers of the posterior tubercle and periventricular thalamus.

Keywords

Aging, Animals, Axonal Transport, Brain, Carbocyanines, Cerebrospinal Fluid, Embryo, Nonmammalian, Fluorescent Dyes, Glutamate Decarboxylase, Hypothalamus, Neurons, Neuropeptide Y, Oncorhynchus mykiss, Trout, gamma-Aminobutyric Acid

Medical Subject Headings

Aging; Animals; Axonal Transport; Brain; Carbocyanines; Cerebrospinal Fluid; Embryo, Nonmammalian; Fluorescent Dyes; Glutamate Decarboxylase; Hypothalamus; Neurons; Neuropeptide Y; Oncorhynchus mykiss; Trout; gamma-Aminobutyric Acid

Publication Date

6-1-1997

Publication Title

Cell and tissue research

ISSN

0302-766X

Volume

288

Issue

3

First Page

497

Last Page

507

PubMed ID

9134862

Digital Object Identifier (DOI)

10.1007/s004410050835

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