Biomedical subjects

M Ravaille-Véron

Publications and source records attributed to M Ravaille-Véron.

3 recordsLinked to original sources

PubMed1991

The olfactoretinalis system = terminal nerve?

Immunohistochemistry revealed a distinct terminal nerve (nT) from the olfactoretinalis system (ORS) in several gymnotid species. The ganglion (NOR) of the ORS is a cluster of FMRF-amide immunoreactive neurones located on the olfactory nerve and bulb. The NOR projects to the olfactory bulb and optic nerve but not to the olfactory epithelium. In contrast, the nT is a small substance P or GnRH immunoreactive fibre bundle which originates from a ganglion located rostral to the olfactory epithelium, courses caudally with the olfactory nerve and terminates as glomeruli in the olfactory bulb. Peripherally the ganglion projects to the epithelium of the anterior nostril. Thus, the terminal nerve appears to be a cranial nerve, clearly distinct from the ORS which consequently should no longer be considered as the terminal nerve.

Animals↗

PubMed1991

[Long ascending fibers in the dorsal column of a teleost fish: a disynaptic pathway connecting sense organs to cerebellum].

In spite of the generally accepted opinion that long ascending proprioceptive and tactile fibers do not occur in the spinal dorsal columns of teleost fish, it was demonstrated with degeneration and axonal transport tracing methods that such dorsal column fibers exist in the teleost fish Gnathonemus petersii. These fibers are in fact common spinal afferent fibers originating in spinal ganglion cells. They connect the peripheral sense organs with the lateral funicular nuclei (Fl2) in which the dorsal column fibers terminate, directly through the dorsal columns. In contrast to the dorsal column nuclei of higher vertebrates, the Fl2 nuclei do not project to the diencephalic thalamus but to the caudal lobe and the second lobe (C2) of the corpus cerebelli. Thus, sense organs and cerebellum are connected by a disynaptic pathway. Since the caudal lobe projects directly to the electrosensory lobe, that is, to the target of electrosensory afferents, the presence of a disynaptic pathway in G. petersii suggests the existence of a proprioceptive control of the electrosensory input.

Afferent Pathways↗

PubMed1991

[Extra-bulbar primary olfactory projection in teleost fishes].

Immunohistochemical investigations with anti-substance P antiserum demonstrate the existence of an extensive extrabulbar primary olfactory projection in several gymnotid teleost fish. This projection, never described before, originates in particular primary olfactory bundles which enter with the olfactory nerve into the olfactory bulb. While the bulk of the olfactory fibers end with glomeruli in the glomerular layer of the olfactory bulb, two particular bundles penetrate into the telencephalon and end, without forming glomeruli, in several telencephalic and diencephalic regions. A few fibers run as far as to the hypothalamus. In the light of these findings, the general notion that the primary olfactory projection is limited to the olfactory bulb and forms only glomeruli-like terminals, should be reconsidered.

Animals↗