Limits...
Synaptic connectivity of the cholinergic axons in the olfactory bulb of the cynomolgus monkey.

Liberia T, Blasco-Ibáñez JM, Nácher J, Varea E, Lanciego JL, Crespo C - Front Neuroanat (2015)

Bottom Line: Our results demonstrate that the cholinergic axons form synaptic contacts on interneurons.Although the cholinergic boutons were frequently found in close vicinity of the dendrites of principal cells, we have not found synaptic contacts on them.From a comparative perspective, our data indicate that the synaptic connectivity of the cholinergic circuits is highly preserved in the OB of macrosmatic and microsmatic mammals.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Biology, Department of Cell Biology, University of Valencia Burjassot, Valencia, Spain.

ABSTRACT
The olfactory bulb (OB) of mammals receives cholinergic afferents from the horizontal limb of the diagonal band of Broca (HDB). At present, the synaptic connectivity of the cholinergic axons on the circuits of the OB has only been investigated in the rat. In this report, we analyze the synaptic connectivity of the cholinergic axons in the OB of the cynomolgus monkey (Macaca fascicularis). Our aim is to investigate whether the cholinergic innervation of the bulbar circuits is phylogenetically conserved between macrosmatic and microsmatic mammals. Our results demonstrate that the cholinergic axons form synaptic contacts on interneurons. In the glomerular layer, their main targets are the periglomerular cells, which receive axo-somatic and axo-dendritic synapses. In the inframitral region, their main targets are the granule cells, which receive synaptic contacts on their dendritic shafts and spines. Although the cholinergic boutons were frequently found in close vicinity of the dendrites of principal cells, we have not found synaptic contacts on them. From a comparative perspective, our data indicate that the synaptic connectivity of the cholinergic circuits is highly preserved in the OB of macrosmatic and microsmatic mammals.

No MeSH data available.


Related in: MedlinePlus

VAChT-staining in the external plexiform layer and in the inframitral region under light microcopy. (A) A varicose axon containing VAChT (arrows) crosses the external plexiform layer (EPL) perpendicularly to the bulbar lamination. The glomerular layer (GL) is shown in the upper side of the micrograph. (B) VAChT-containing fibers (arrows) running throughout the superficial portion of the granule cell layer (GCL). Note that some fibers run parallel and others perpendicularly to the bulbar lamination. Scale bar: 30 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4362316&req=5

Figure 3: VAChT-staining in the external plexiform layer and in the inframitral region under light microcopy. (A) A varicose axon containing VAChT (arrows) crosses the external plexiform layer (EPL) perpendicularly to the bulbar lamination. The glomerular layer (GL) is shown in the upper side of the micrograph. (B) VAChT-containing fibers (arrows) running throughout the superficial portion of the granule cell layer (GCL). Note that some fibers run parallel and others perpendicularly to the bulbar lamination. Scale bar: 30 μm.

Mentions: The external plexiform layer contained some VAChT-positive axons. Many of them were found ascending from the inframitral region. They crossed the external plexiform layer perpendicularly to the lamination of the OB and reached the glomerular layer (Figure 3A). The inframitral region, which includes the internal plexiform layer and the granule cell layer, contained a high density of VAChT-positive axons. Most of them were oriented in parallel to the lamination of the OB and distributed within the rows of granule cells (Figure 3B). However, some axons were oriented perpendicularly to the bulbar lamination, crossing the mitral cell layer and ascending towards the external plexiform layer.


Synaptic connectivity of the cholinergic axons in the olfactory bulb of the cynomolgus monkey.

Liberia T, Blasco-Ibáñez JM, Nácher J, Varea E, Lanciego JL, Crespo C - Front Neuroanat (2015)

VAChT-staining in the external plexiform layer and in the inframitral region under light microcopy. (A) A varicose axon containing VAChT (arrows) crosses the external plexiform layer (EPL) perpendicularly to the bulbar lamination. The glomerular layer (GL) is shown in the upper side of the micrograph. (B) VAChT-containing fibers (arrows) running throughout the superficial portion of the granule cell layer (GCL). Note that some fibers run parallel and others perpendicularly to the bulbar lamination. Scale bar: 30 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4362316&req=5

Figure 3: VAChT-staining in the external plexiform layer and in the inframitral region under light microcopy. (A) A varicose axon containing VAChT (arrows) crosses the external plexiform layer (EPL) perpendicularly to the bulbar lamination. The glomerular layer (GL) is shown in the upper side of the micrograph. (B) VAChT-containing fibers (arrows) running throughout the superficial portion of the granule cell layer (GCL). Note that some fibers run parallel and others perpendicularly to the bulbar lamination. Scale bar: 30 μm.
Mentions: The external plexiform layer contained some VAChT-positive axons. Many of them were found ascending from the inframitral region. They crossed the external plexiform layer perpendicularly to the lamination of the OB and reached the glomerular layer (Figure 3A). The inframitral region, which includes the internal plexiform layer and the granule cell layer, contained a high density of VAChT-positive axons. Most of them were oriented in parallel to the lamination of the OB and distributed within the rows of granule cells (Figure 3B). However, some axons were oriented perpendicularly to the bulbar lamination, crossing the mitral cell layer and ascending towards the external plexiform layer.

Bottom Line: Our results demonstrate that the cholinergic axons form synaptic contacts on interneurons.Although the cholinergic boutons were frequently found in close vicinity of the dendrites of principal cells, we have not found synaptic contacts on them.From a comparative perspective, our data indicate that the synaptic connectivity of the cholinergic circuits is highly preserved in the OB of macrosmatic and microsmatic mammals.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Biology, Department of Cell Biology, University of Valencia Burjassot, Valencia, Spain.

ABSTRACT
The olfactory bulb (OB) of mammals receives cholinergic afferents from the horizontal limb of the diagonal band of Broca (HDB). At present, the synaptic connectivity of the cholinergic axons on the circuits of the OB has only been investigated in the rat. In this report, we analyze the synaptic connectivity of the cholinergic axons in the OB of the cynomolgus monkey (Macaca fascicularis). Our aim is to investigate whether the cholinergic innervation of the bulbar circuits is phylogenetically conserved between macrosmatic and microsmatic mammals. Our results demonstrate that the cholinergic axons form synaptic contacts on interneurons. In the glomerular layer, their main targets are the periglomerular cells, which receive axo-somatic and axo-dendritic synapses. In the inframitral region, their main targets are the granule cells, which receive synaptic contacts on their dendritic shafts and spines. Although the cholinergic boutons were frequently found in close vicinity of the dendrites of principal cells, we have not found synaptic contacts on them. From a comparative perspective, our data indicate that the synaptic connectivity of the cholinergic circuits is highly preserved in the OB of macrosmatic and microsmatic mammals.

No MeSH data available.


Related in: MedlinePlus