Search results for "Terminal"

Terminal end of the human odontoblast processes

2000

<p class="HeadingRunIn"><strong>A review of the genus <em>Discomyza </em>(Diptera: Ephydridae) from Afrotropical, Australasia…

2015

Tropical Old World species of the genus Discomyza are redescribed, including male terminalia, photographs of heads and wings. One new species Discomyza fagomoga sp. nov. is described from D. R. Congo, Ethiopia, Kenya and Uganda. Two new synonyms are proposed: Discomyza obscuricornis Canzoneri and Rampini, 1996 = D. dolichocerus Cresson, 1944 and D. intermedia Canzoneri and Meneghini, 1969 = D. eritrea Cresson, 1939. A key to all species is provided. Relationships among species of Discomyza are suggested.

Ontogenesis of the Extra-Bulbar Olfactory Pathway inXenopus laevis

2013

Although the development, anatomy, and physiology of the vertebrate olfactory system are fairly well understood, there is still no clear definition of the terminal nerve complex acknowledged by all. Among the most debated matters is whether or not the extrabulbar projections found in anamniotes should or should not be considered part of the terminal nerve complex. In this context, we investigated the early development of the extrabulbar pathway in Xenopus larvae from placodal differentiation to postmetamorphic stages. We showed that the extrabulbar fibers become visible around Stage 42 and are conserved throughout metamorphosis. We confirmed previous reports concerning their central project…

Afferent and efferent connections of the olfactory bulbs in the lizard Podarcis hispanica.

1991

The connections of the olfactory bulbs of Podarcis hispanica were studied by tract-tracing of injected horseradish peroxidase. Restricted injections into the main olfactory bulb (MOB) resulted in bilateral terminallike labeling in the medial part of the anterior olfactory nucleus (AON) and in the rostral septum, lateral cortex, nucleus of the lateral olfactory tract, and ventrolateral amygdaloid nucleus. Bilateral retrograde labeling was found in the rostral lateral cortex and in the medial and dorsolateral AON. Ipsilaterally the dorsal cortex, nucleus of the diagonal band, lateral preoptic area, and dorsolateral amygdala showed labeled cell bodies. Retrogradely labeled cells were also foun…

Characterization of somatostatin- and cholecystokinin-immunoreactive periglomerular cells in the rat olfactory bulb.

2005

Periglomerular cells (PG) are interneurons of the olfactory bulb (OB) that modulate the first synaptic relay of the olfactory information from the olfactory nerve to the dendrites of the bulbar principal cells. Previous investigations have pointed to the heterogeneity of these interneurons and have demonstrated the presence of two different types of PG. In the rat OB, type 1 PG receive synaptic contacts from the olfactory axons and are γ-aminobutyric acid (GABA)-ergic, whereas type 2 PG do not receive synaptic contacts from the olfactory axons and are GABA immunonegative. In this study, we analyze and characterize neurochemically a group of PG that has not been previously classified either …

Synaptic connectivity of serotonergic axons in the olfactory glomeruli of the rat olfactory bulb.

2010

Although the major mode of transmission for serotonin in the brain is volume transmission, previous anatomical studies have demonstrated that serotonergic axons do form synaptic contacts. The olfactory glomeruli of the olfactory bulb of mammals receive a strong serotonergic innervation from the dorsal and medial raphe nuclei. In the present report, we investigate the synaptic connectivity of these serotonergic axons in the glomerular neuropil of the rat olfactory bulb. Our study shows that serotonergic axons form asymmetrical synaptic contacts on dendrites within the glomerular neuropil. Analyzing the neurochemical nature of the synaptic targets, we have found that 55% of the synapses were …

Segregated pathways to the vomeronasal amygdala: differential projections from the anterior and posterior divisions of the accessory olfactory bulb.

2007

Apically and basally located receptor neurons in the vomeronasal sensory epithelium express G(i2 alpha)- and G(o alpha)-proteins, V1R and V2R vomeronasal receptors, project to the anterior and posterior accessory olfactory bulb and respond to different stimuli, respectively. The extent to which secondary projections from the two portions of the accessory olfactory bulb are convergent in the vomeronasal amygdala is controversial. This issue is addressed by using anterograde and retrograde tract-tracing methods in rats including electron microscopy. Injections of dextran-amines, Fluoro Gold, cholera toxin-B subunit and Fast Blue were delivered to the anterior and posterior accessory olfactory…

Neural Substrate to Associate Odorants and Pheromones: Convergence of Projections from the Main and Accessory Olfactory Bulbs in Mice

2012

In rodents olfactory stimuli are essential for socio-sexual behaviour. Volatile stimuli mainly activate the main olfactory system, whereas non-volatile ones, some of them considered as pheromones, activate the accessory olfactory system. Traditionally, it has been considered that the efferent projections of the main and the accessory olfactory bulbs innervate different telencephalic areas. Recent studies performed in rats and mice have challenged this view. In this work we explore in mice, through the use of anterograde tracer injections in the olfactory bulbs, the brain centres where olfactory and vomeronasal information might converge.

Fiber Connections of the Amygdaloid Formation of the Lizard <i>Podarcis hispanica</i>

1993

The amygdaloid formation of the lizard Podarcis hispanica can be divided into three main groups of nuclei on the basis of their input from the main and accessory olfactory bulbs: the vomeronasal amygdala, the olfactory amygdala and the dorsal amygdaloid group, the latter group receiving afferents from neither the main (MOB) or the accessory olfactory bulb (AOB). The vomeronasal amygdala has a centrifugal projection to the AOB, an important commissural connection to the contralateral vomeronasal amygdala, a minor projection to nucleus accumbens, and a bilateral projection to the lateral cortex. The olfactory amygdala displays a bilateral afferents from the MOB, receives a contralateral affer…

Nitric oxide synthase containing periglomerular cells are GABAergic in the rat olfactory bulb.

2003

In the olfactory glomeruli of the rat olfactory bulb, there is a population of periglomerular cells (PG) that contains the neuronal isoform of the nitric oxide synthase (nNOS). To date, these PG have not been characterized neurochemically and it has not been determined whether they are type 1 (GABAergic PG that receive synaptic contacts from the olfactory axons) or type 2 PG (non-GABAergic PG that do not receive synapses from the olfactory axons). Combining pre-embedding NADPH-diaphorase histochemistry and post-embedding immunoperoxidase detection of GABA, we demonstrate that nNOS-containing PG are GABAergic and therefore, belong to the type 1 PG. The possible actions of nitric oxide in the…