Some primary olfactory axons project to the contralateral olfactory bulb in Xenopus laevis

Ebbesson, Sven O. E.; Bazer, Gary T.; Jane, John A.

doi:10.1016/0304-3940(86)90311-3

Cited by 19 publications

(10 citation statements)

References 7 publications

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“…This connection was not detected in the chondrostean Scaphirhynchus by degeneration techniques (Braford, 1975; Northcutt and Braford, 1980). Contralateral bulbar connections have been previously reported in agnathans (Wicht and Northcutt, 1993; Polenova and Vesselkin, 1993), chondrichthyes (Smeets, 1983), teleosts (Bass, 1981a,Bass, 1981b; Ebbesson et al, 1981; von Bartheld et al, 1984; Levine and Dethier, 1985; Matz, 1995; Riedel and Krug, 1997), and anurans (Ebbesson et al, 1986). In teleosts, this projection is related to the medial olfactory tract, which carries most of the bulbar afferents.…”

Section: Discussionmentioning

confidence: 83%

Olfactory projections in a chondrostean fish,Acipenser baeri: An experimental study

Huesa

Anadón²,

Yáñez³

2000

J. Comp. Neurol.

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The presence of extrabulbar primary olfactory projections has been well established in teleosts. In order to investigate the phylogeny of these projections and to compare their targets with those of the secondary olfactory projections, the connections of the olfactory epithelium and olfactory bulb were studied by means of tract-tracing methods in a chondrostean, Acipenser baeri. Primary olfactory projections mainly extend to the glomerular layer of the olfactory bulb, but a significant number of extrabulbar efferent fibers course to various telencephalic and diencephalic regions. Both extrabulbar primary and olfactory bulb projections course in diffuse pathways. Extensive overlap was observed between the targets of these extrabulbar primary olfactory fibers and those of the secondary efferent projections of the olfactory bulb, though the latter were more numerous and reached additional targets. Tracer application to the olfactory bulb also revealed a number of bulbopetal neurons in the ipsilateral and contralateral telencephalic areas, as well as crossed interbulbar projections. The presence in a chondrostean of important extrabulbar primary projections and their extensive overlap with secondary olfactory projections suggest that such projections are a derived characteristic of bony fishes.

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Section: Discussionmentioning

confidence: 83%

Olfactory projections in a chondrostean fish,Acipenser baeri: An experimental study

Huesa

Anadón²,

Yáñez³

2000

J. Comp. Neurol.

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“…Through primary (directly) or basal (indirectly) dendrites, a single mitral cell can innervate several widely separated glomeruli, including contralateral ones (Ebbesson et al 1986;Kemali and Guglielmotti 1987;Scalia et al 1991 ;Jiang and Holley 1992;Leveteau et al, 1992). This is not the case in mammals, where all mitral cell output is ipsilateral.…”

Section: Amphibians Reptilesmentioning

confidence: 99%

Mitral cell dendrites: a comparative approach

Dryer

Graziadei

1994

Anat Embryol

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Phylogenetically persistent structures such as the mitral cells of the vertebrate olfactory bulb undergo changes in their dendritic arbor in the course of evolution. The morphology of mitral cells and the main elements of the olfactory bulb circuit in all classes of vertebrates are reviewed in this paper. Most of the neuronal elements found in the mammalian olfactory bulb are present in anamniotes. However, in contrast to those of amniotes, the mitral cells of most anamniotes lack basal dendrites, and periglomerular cells are absent in fish. This suggests a different circuitry and therefore drastic changes in the processing of olfactory information within the olfactory bulb. Lateral inhibition, conferred by basal dendrites in anamniotes, must then utilize other mechanisms in anamniotes. Moreover, the marked segregation of olfactory inputs onto mammalian mitral cells is less obvious in mitral cells of anamniotes that lack basal dendrites. The general role of dendrites, including those of mitral cells, is discussed in the light of increasing evidence for dendritic excitability. The evolutionary significance of mitral cell basal dendrites is also discussed.

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“…Their small, fused olfactory bulb could thus be a sign of evolutionary degeneration of olfactory function. In anurans, the fused olfactory bulb has been described in different species (Hoffman, 1963; Ebbesson et al, 1986; Scalia et al, 1991; Jiang and Holley, 1992b), independently of their habitat and the degrees to which they rely on olfaction. It seems thus unlikely that the fusion of the olfactory bulb can be interpreted as a sign of olfactory degeneration in the anurans as well.…”

Section: Discussionmentioning

confidence: 99%

Distinct interhemispheric connectivity at the level of the olfactory bulb emerges during Xenopus laevis metamorphosis

Weiß

Arias

Offner

et al. 2021

Preprint

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The olfactory system of anuran tadpoles requires substantial restructuring to adapt to the lifestyle of the adult frogs. Xenopus laevis tadpoles have a single main olfactory epithelium in the principal nasal cavity associated with aquatic olfaction. After metamorphosis, this epithelial surface is transformed into the adult air-nose and a new epithelium, the adult water-nose, is present in the middle cavity. Impacts of this massive remodeling on odor processing, behavior and network structure are still unexplored. In the present study, we used neuronal tracings, calcium imaging and a behavioral assay to examine the functional connectivity between the epithelium and the main olfactory bulb during metamorphosis. In tadpoles, olfactory receptor neurons in the principal cavity epithelium project axons to glomeruli in the ventral main olfactory bulb. During metamorphosis, these projections are gradually replaced by receptor neuron axons emerging from the newly forming middle cavity epithelium. Despite this metamorphotic reorganization in the ventral bulb, two spatially and functionally segregated odor processing streams remain undisrupted. In line with this, metamorphotic rewiring does not alter behavioral responses to waterborne odorants. Contemporaneously, newly formed receptor neurons in the remodeling principal cavity epithelium project their axons to the dorsal part of the bulb. The emerging neuronal networks of the dorsal and ventral main olfactory bulb show substantial differences. Glomeruli around the midline of the dorsal bulb are innervated from the left and right nasal epithelia. In addition, postsynaptic projection neurons in the dorsal bulb predominantly have smaller tufts and connect to multiple glomeruli, while more than half of projection neurons in the ventral bulb have a single, bigger tuft. Our results show that during the metamorphotic reconstruction of the olfactory network the water system remains functional. Differences of the neuronal network of the dorsal and ventral olfactory bulb imply that a higher degree of odor integration takes place in the dorsal main olfactory bulb. This is likely connected with the processing of different odorants, airborne vs. waterborne, in these two parts of the olfactory bulb.

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Some primary olfactory axons project to the contralateral olfactory bulb in Xenopus laevis

Cited by 19 publications

References 7 publications

Olfactory projections in a chondrostean fish,Acipenser baeri: An experimental study

Olfactory projections in a chondrostean fish,Acipenser baeri: An experimental study

Mitral cell dendrites: a comparative approach

Distinct interhemispheric connectivity at the level of the olfactory bulb emerges during Xenopus laevis metamorphosis

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