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PubMed1985

The connections between the olfactory bulb and the brain in the goldfish.

We have investigated olfactory bulb connections in the goldfish by using both horseradish peroxidase applied to olfactory tract lesions and wheat germ agglutinin-conjugated peroxidase administered to the olfactory bulb. The projections from the bulb pass to the brain in two major bundles: the lateral and the medial olfactory tracts. The lateral tract innervates the posterior terminal field in the area dorsalis. The medial tract divides into two rami. The dorsolateral ramus is the most substantial olfactory bundle in the brain and innervates several targets in both the area dorsalis and the area ventralis. The ventromedial ramus appears to innervate targets in the area ventralis exclusively. In addition, fibers of the medial olfactory tract (both rami) innervate the preoptic nucleus as well as targets in the diencephalon and, possibly, in the mesencephalon as well. Olfactory fibers from the dorsolateral and ventro-medial rami cross the midline in the dorsal and ventral olfactory decussations, respectively. Between these two decussations is a dense olfactory plexus which has not previously been reported, and which may serve as a nexus allowing interchange of fibers between the two olfactory rami. The terminal nerve in the goldfish has two parts. The major part of the nerve projects to the ventral nucleus (Vv) and is far more extensive than has previously been reported. A much less substantial component of the terminal nerve projects to the two retinae. There are four large groups of cells in the telencephalon which project to the olfactory bulb. Of these two, the dorsal and the anterolateral groups have not been described in previous studies of the goldfish. We also report weakly labeled bulbopetal cells in the nucleus preglomerulosus and in the locus ceruleus.

Afferent Pathways↗
PubMed1984

Sexual behavior and aggression in male mice: involvement of the vomeronasal system.

Recent observations have implicated the vomeronasal (accessory olfactory) system in the chemosensory control of rodent social behaviors. The purpose of this study was to observe the effects of peripheral vomeronasal organ extirpation on sexual behavior, aggression, and urine marking in male mice. Relative to sham-operated control animals, mice lacking vomeronasal organs displayed significantly reduced levels of copulatory behavior and intermale aggression. Urine marking rates were not reduced. The peripheral removal of the vomeronasal organ resulted in complete bilateral deafferentation of the accessory olfactory bulbs but spared the peripheral input to the main olfactory bulbs as evidenced by the lack of anterograde vomeronasal nerve transport but normal anterograde olfactory nerve transport of intranasally applied horseradish peroxidase. Neither body weights, paired testes weights, nor seminal vesicle weights of mice with vomeronasal system lesions differed significantly from those of control animals. Thus, an intact vomeronasal organ is important for the normal display of sexual behavior and aggression in male mice, and the reductions in these androgen-dependent behaviors following peripheral deafferentation of the vomeronasal system cannot be attributed to a chronic reduction of gonadal hormone secretion.

Aggression↗
PubMed1990

Interspecies differences in the substance P- and vasoactive intestinal polypeptide-like immunoreactivities in the olfactory bulb of Salmo gairdneri and Barbus meridionalis.

The distribution of substance P-like (SP) and vasoactive intestinal polypeptide-like (VIP) structures was studied using an indirect immunoperoxidase technique in the mediterranean barbel Barbus meridionalis and in the rainbow trout Salmo gairdneri. SP-like positive fibers were observed in the inner strata of the mediterranean barbel olfactory bulb, mainly the granule cell and the plexiform layers. Ganglion cells and fibers of the terminal nerve were also labeled. No SP-positive structure was found in the olfactory bulb of the rainbow trout. On the contrary, the VIP antiserum used displayed very strong immunostaining in the olfactory nerve fiber layer of Salmo gairdneri, whereas those fibers in Barbus meridionalis showed no immunoreactivity. After a complete transection of the olfactory tract and a survival time of 20 days, SP-immunostained fibers were not observed. Thus, they can presumably be identified as centrifugal fibers, coursing from the telencephalic hemispheres through the olfactory tracts, into the olfactory bulb. The VIP immunoreactivity was confined to the olfactory fibers, both in the olfactory nerve and the olfactory bulb. The positive immunostaining disappeared after chemical lesion of the olfactory mucosa. These observations demonstrate that the olfactory bulb of freshwater teleosts exhibits a high degree of heterogeneity in its immunocytochemical distribution pattern, this pattern also differing from previous reports on higher vertebrates.

Animals↗
PubMed1998

Lectin binding patterns in the vomeronasal organ and accessory olfactory bulb of the rat.

A number of previous studies have indicated that lectin histochemistry is an obvious choice for characterizing the vomeronasal system. However, apparently inconsistent results have been obtained: notably, the affinity with which various lectins bind to the accessory olfactory bulb varies among taxa, even considering closely related species. In the present study, the binding patterns of seven lectins in the rat accessory olfactory bulb, vomeronasal nerves and vomeronasal duct were investigated. The Bandeiraea simplicifolia lectin bound exclusively to the vomeronasal nerve and glomerular layers of the accessory olfactory bulb, while the Ulex europeus and Lycopersicon esculentum lectins bound to these regions and additionally to the nerve and glomerular layers of the main olfactory bulb. Soybean agglutinin showed a similar pattern to that obtained with the Ulex europeus and Lycopersicon esculentum lectins, though it also faintly labelled other parts of the structures examined. The Vicia villosa and Erythrina cristagalli lectins were not specific for the vomeronasal system, since they labelled grey and white matters in structures including the lateral olfactory tract and the anterior olfactory nuclei. The Dolichos biflorus lectin did not bind to vomeronasal tissues. The observed patterns of binding in the accessory olfactory bulb were consistent with those observed in the vomeronasal nerves, but unlike those observed in the epithelium of the vomeronasal duct. This latter result probably reflects binding of lectins to sugar residues contained in secreted mucus rather than those in epithelial nerve endings.

Animals↗
PubMed1998

Age-related size reduction of foramina in the cribriform plate.

Anecdotal evidence suggests that the foramina of the cribriform plate which transmit cranial nerve I decrease in size with age, but this finding has never been supported with quantitative data. It has also been observed that olfactory function declines with increasing age. It has been hypothesized that the cribriform plate foramina closure may be responsible for the olfactory performance decrease with age. We gathered quantitative data to test an age-related decline in cribriform plate foramina area. We report data for the area of patent foramina in the posterior 1 cm of 57 cribriform plates from 40 skulls of known age and sex. Analyses were performed to test for the effects of age, sex, and lateralization on foramina area. The area of patent foramina in the cribriform plate decreases with increasing age. Age is a strong covariate with foramina area (P value = 0.0025). The regression equation for the area of patent foramina is: expected area = 8.17 - (0.06) age. Adding the variable sex does not contribute significantly (P value > 0.28) to the model which utilizes age alone. Nor was there any significant lateralization in patent foramina area. The area of patent foramina in the cribriform plate decreases with increasing age, and there is no significant difference between males and females or left and right sides. Such decreases in patent foramina may be associated with impaired olfactory function in the aged.

Adult↗
PubMed2006

Immunohistochemical localization of vascular endothelial growth factor and its receptor Flk-1 in the amphibian developing principal and accessory olfactory system.

In the last years several studies have shown that vascular endothelial growth factor (VEGF) is present in neural stem cells and mature neurons from different neural tissues where it may play an important role as a neuroproliferative and/or antiapoptotic factor. The olfactory neuroepithelium has the capability to replace dying neurons with new neurons formed by cell division from stem cells in the basal region of the epithelium. The present study demonstrates, for the first time, that VEGF is present in the olfactory epithelium, nerves and bulbs (both main and accessory) during the development of the toad Bufo arenarum. In this report, we detected VEGF immunoreactivity in mature olfactory neurons from early larval stages until the beginning of the metamorphic climax. VEGF expression decreases dramatically after metamorphosis. VEGF receptor Flk-1 was localized by immunohistochemistry, from premetamorphic larval stages until the climax in the neurons of the olfactory epithelium with a more intense labeling in the basal cell layer. Double-label immunofluorescence studies localized VEGF to the cytoplasm and the nucleus of mature neurons whereas Flk-1 was expressed in cell membranes. Flk-1 was present in neurons of both the main and accessory olfactory bulbs. After the end of metamorphosis, Flk-1 expression was limited to basal cells in the olfactory epithelium and Bowman's glands. The main and accessory olfactory bulbs showed the same pattern of Flk-1 immunostaining before and after the end of metamorphosis. The presence of VEGF and its receptor in the olfactory system suggests that VEGF may play an important role during neural development.

Animals↗
PubMed1988

[Role of radiotherapy in esthesioneuroblastoma].

A case report on a locally advanced inoperable esthesioneuroblastoma in a patient of 65 years of age is presented. Chemotherapy (CYVADIC) resulted in a slight reduction of tumour mass and was followed by rapid tumour regrowth. By megavoltage radiotherapy (65 Gy) with shrinking field technique a clinically complete remission was achieved. The role of radiotherapy in long-term local tumour control in combination with surgery is discussed, taking into account the few date reported in literature. Depending on the tumour stage at diagnosis, a graduated strategy combining surgery and radiotherapy is recommended as the treatment of choice. The value of adjuvant chemotherapy has not yet been clearly established, not even in locally progressing or advanced stages of tumours or in metastasizing tumours.

Aged↗
PubMed1983

The re-innervation of olfactory glomeruli following transection of primary olfactory axons in the central or peripheral nervous system.

The re-innervation of the olfactory bulb has been studied in rats in which the primary afferent axons were transected either in the peripheral nervous system, on the intracranial side of the cribriform plate, or in the central nervous system, in the nerve fibre layer of the bulb. Both procedures resulted in denervation of glomeruli on the dorsal surface of the olfactory bulb. Re-innervation of these glomeruli was first seen approximately three weeks after operation and was largely completed by the sixth week, irrespective of the site of the lesion. The similarity of the timing of re-innervation following the two procedures indicates that the cut fibres did not regenerate from their sites of transection. It is much more probable that the re-innervation axons were those of neurons newly generated in the olfactory epithelium. This view is supported by the results of other investigations, in which retrograde degeneration and subsequent replacement of the neurons have been found to follow transection of the olfactory nerves. After transection of the olfactory nerves, the new axons entering the bulb grew through the site of the lesion, across the interface between peripheral and central nervous tissue, through the nerve fibre layer and into the glomeruli. Thus, they followed the same course as normally growing primary olfactory axons. After the afferent fibres had been cut within the olfactory bulb, the site of transection was transformed into a scar composed largely of astrocytes. No olfactory axons grew through the scar and none passed beneath it in the deeper layers of the bulb. However, by tracing the anterograde axonal transport of horseradish peroxidase, it has been shown that axons immediately rostral to the lesion terminated in the re-innervated glomeruli. These denervated glomeruli were, therefore, probably re-innervated by axons that grew through the intact central nervous tissue of the nerve fibre layer on either side of the lesion.

Animals↗