Dissecting the neural divide: A continuous neurectoderm gives rise to both the olfactory placode and olfactory bulb

2020 ◽  
Vol 52 ◽  
Author(s):  
Jorge Torres-Paz ◽  
Eugene Mbar Tine ◽  
Kathleen E. Whitlock
Keyword(s):  
Nervous System ◽  
Olfactory Bulb ◽  
Morphological Changes ◽  
Large Field ◽  
Olfactory Bulbs ◽  
Cell Movements ◽  
Olfactory Placode ◽  
The Central Nervous System ◽  
Continuous Sheet ◽  
Olfactory Organs

The olfactory epithelia arise from morphologically identifiable structures called olfactory placodes. Sensory placodes are generally described as being induced from the ectoderm suggesting that their development is separate from the coordinated cell movements generating the central nervous system. Previously, we have shown that the olfactory placodes arise from a large field of cells bordering the telencephalic precursors in the neural plate, and that cell movements, not cell division, underlie olfactory placode morphogenesis. Subsequently by image analysis, cells were tracked as they moved in the continuous sheet of neurectoderm giving rise to the peripheral (olfactory organs) and central (olfactory bulbs) nervous system (Torres-Paz and Whitlock, 2014). These studies lead to a model whereby the olfactory epithelia develop from within the border of the neural late and are a neural tube derivative, similar to the retina of the eye (Torres-Paz and Whitlock, 2014; Whitlock, 2008). Here we show that randomly generated clones of cells extend across the morphologically differentiated olfactory placodes/olfactory bulbs, and test the hypothesis that these structures are patterned by a different level of distal-less (dlx) gene expression subdividing the anterior neurectoderm into OP precursors (high Dlx expression) and OB precursors (lower Dlx expression). Manipulation of DLX protein and RNA levels resulted in morphological changes in the size of the olfactory epithelia and olfactory bulb. Thus, the olfactory epithelia and bulbs arise from a common neurectodermal region and develop in concert through coordinated morphological movements.

Molecular Biology of Vertebrate Olfactory Receptors and Circuits

2021 ◽  
Author(s):  
Richard P. Tucker ◽  
Qizhi Gong
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Olfactory Bulb ◽  
Gene Family ◽  
Sensory Neuron ◽  
Sensory Neurons ◽  
Odorant Receptor ◽  
Vomeronasal Organ ◽  
Odorant Receptors ◽  
The Central Nervous System

Animals use their olfactory system for the procurement of food, the detection of danger, and the identification of potential mates. In vertebrates, the olfactory sensory neuron has a single apical dendrite that is exposed to the environment and a single basal axon that projects to the central nervous system (i.e., the olfactory bulb). The first odorant receptors to be discovered belong to an enormous gene family encoding G protein-coupled seven transmembrane domain proteins. Odorant binding to these classical odorant receptors initiates a GTP-dependent signaling cascade that uses cAMP as a second messenger. Subsequently, additional types of odorant receptors using different signaling pathways have been identified. While most olfactory sensory neurons are found in the olfactory sensory neuroepithelium, others are found in specialized olfactory subsystems. In rodents, the vomeronasal organ contains neurons that recognize pheromones, the septal organ recognizes odorant and mechanical stimuli, and the neurons of the Grüneberg ganglion are sensitive to cool temperatures and certain volatile alarm signals. Within the olfactory sensory neuroepithelium, each sensory neuron expresses a single odorant receptor gene out of the large gene family; the axons of sensory neurons expressing the same odorant receptor typically converge onto a pair of glomeruli at the periphery of the olfactory bulb. This results in the transformation of olfactory information into a spatially organized odortopic map in the olfactory bulb. The axons originating from the vomeronasal organ project to the accessory olfactory bulb, whereas the axons from neurons in the Grüneberg ganglion project to 10 specific glomeruli found in the caudal part of the olfactory bulb. Within a glomerulus, the axons originating from olfactory sensory neurons synapse on the dendrites of olfactory bulb neurons, including mitral and tufted cells. Mitral cells and tufted cells in turn project directly to higher brain centers (e.g., the piriform cortex and olfactory tubercle). The integration of olfactory information in the olfactory cortices and elsewhere in the central nervous system informs and directs animal behavior.

Olfactory Bulb

2017 ◽  
pp. 309-322
Author(s):  
Gordon M. Shepherd ◽  
Michele Migliore ◽  
Francesco Cavarretta
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Visual Cortex ◽  
Olfactory Bulb ◽  
Primary Visual Cortex ◽  
Antennal Lobe ◽  
Cell Types ◽  
Synaptic Interactions ◽  
The Central Nervous System ◽  
Olfactory Input

The olfactory bulb is the site of the first synaptic processing of the olfactory input from the nose. It is present in all vertebrates (except cetaceans) and a the analogous antennal lobe in most invertebrates. With its sharply demarcated cell types and histological layers, and some well-studied synaptic interactions, it is one of the first and clearest examples of the microcircuit concept in the central nervous system. The olfactory bulb microcircuit receives the information in the sensory domain and transforms it into information in the neural domain. Traditionally, it has been considered analogous to the retina in processing its sensory input, but that has been replaced by the view that it is more similar to the thalamus or primary visual cortex in processing its multidimensional input. This chapter describes the main synaptic connections and functional operations and how they provide the output to the olfactory cortex

Morphofunctional Indicators of the Effects of Protons on the Central Nervous System

2019 ◽  
pp. 75-81
Author(s):  
К. Ляхова ◽  
K. Lyakhova ◽  
И. Колесникова ◽  
I. Kolesnikova ◽  
Д. Утина ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Purkinje Cells ◽  
Hippocampal Neurons ◽  
Morphological Changes ◽  
Early Period ◽  
The State ◽  
High Plasticity ◽  
The Central Nervous System ◽  
Accelerated Protons

Purpose: Investigation of the dose–time–effect dependency of the behavior of mice and rats after irradiation with accelerated protons and comparison of these data with the morphological changes in the hippocampus and the cerebellum of rodents. Material and methods: Experiments were performed on outbred adult female ICR mice (CD-1), SPF categories, body weight 30–35 g, of the age of 10 weeks – total number 61 animals, and on 39 male Sprague Dawley outbred rats weighing 190–230 g, aged 6.5–7.5 weeks. The animals were irradiated with accelerated protons with energy of 70 MeV on the medical beam of the phasotron of the Joint Institute for Nuclear Research (Dubna). Mice were placed in individual containers and irradiated 4 ones at a time. Irradiation was performed in a modified Bragg peak at doses of 0.5; 1; 2.5 and 5 Gy in caudocranial and craniocaudal direction. Rats were divided into 2 groups: intact control and group irradiated with 170 MeV protons at a dose of 1 Gy, dose rate of 1 Gy / min in the craniocaudal direction. The behavioral responses of experimental animals were tested in the Open Field test on days 1, 7, 14, 30, 90 in rats and on days 8, 30, and 90 in mice. Quantitative analysis of the dilution of Purkinje cells in the rat cerebellum was made, as well as morphological changes in the rat hippocampal neurons. It was shown a development of structural changes after irradiation with protons in neurons of different severity at different times after exposure: after 30 and 90 days. Results: In the period of 1–8 days after proton irradiation of mice and rats in non-lethal doses (0.5–5.0 Gy), there is a dose-independent decrease in the main indicators of the spontaneous locomotor activity of rodents. By the 90th day after irradiation, there is a clear tendency to normalize the indicators of OIR in all groups of irradiated animals, while the ES remains elevated. Disruption of motor activity of rodents irradiated with protons in the early period and its relative normalization in the late post-irradiation period occur on the background of an increased number of morphologically altered and dystrophic neurons in the hippocampus and rarefied of Purkinje cells in the cerebellum. Conclusion: The complex hierarchical structure of the central nervous system, the dependence of its function on the state of the whole organism and its hormonal background, as well as on the state of the blood supply and other factors, along with its high plasticity, require complex physiological, morphological and neurochemical approaches in analyzing the radiobiological effect of corpuscular radiation, taking into consideration the unevenness in dose distribution during irradiation.

scholarly journals Free Sialic Acid Acts as a Signal That Promotes Streptococcus pneumoniae Invasion of Nasal Tissue and Nonhematogenous Invasion of the Central Nervous System

2016 ◽  
Vol 84 (9) ◽  
pp. 2607-2615 ◽  
Author(s):  
Brandon L. Hatcher ◽  
Joanetha Y. Hale ◽  
David E. Briles
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Streptococcus Pneumoniae ◽  
Sialic Acid ◽  
Bacterial Meningitis ◽  
Imaging System ◽  
Pneumococcal Infection ◽  
Acute Bacterial Meningitis ◽  
Olfactory Bulbs ◽  
The Central Nervous System

Streptococcus pneumoniae(pneumococcus) is a leading cause of bacterial meningitis and neurological sequelae in children worldwide. Acute bacterial meningitis is widely considered to result from bacteremia that leads to blood-brain barrier breakdown and bacterial dissemination throughout the central nervous system (CNS). Previously, we showed that pneumococci can gain access to the CNS through a nonhematogenous route without peripheral blood infection. This access is thought to occur when the pneumococci in the upper sinus follow the olfactory nerves and enter the CNS through the olfactory bulbs. In this study, we determined whether the addition of exogenous sialic acid postcolonization promotes nonhematogenous invasion of the CNS. Previously, others showed that treatment with exogenous sialic acid post-pneumococcal infection increased the numbers of CFU recovered from an intranasal mouse model of infection. Using a pneumococcal colonization model, anin vivoimaging system, and a multiplex assay for cytokine expression, we demonstrated that sialic acid can increase the number of pneumococci recovered from the olfactory bulbs and brains of infected animals. We also show that pneumococci primarily localize to the olfactory bulb, leading to increased expression levels of proinflammatory cytokines and chemokines. These findings provide evidence that sialic acid can enhance the ability of pneumococci to disseminate into the CNS and provide details about the environment needed to establish nonhematogenous pneumococcal meningitis.

scholarly journals Nonlesions, Unusual Cell Types, and Postmortem Artifacts in the Central Nervous System of Domestic Animals

2012 ◽  
Vol 50 (1) ◽  
pp. 122-143 ◽  
Author(s):  
P. Wohlsein ◽  
U. Deschl ◽  
W. Baumgärtner
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Area Postrema ◽  
Morphological Changes ◽  
Subcommissural Organ ◽  
Cell Types ◽  
Domestic Animals ◽  
Circumventricular Organs ◽  
Polyglucosan Bodies ◽  
The Central Nervous System

In the central nervous system (CNS) of domestic animals, numerous specialized normal structures, unusual cell types, findings of uncertain or no significance, artifacts, and various postmortem alterations can be observed. They may cause confusion for inexperienced pathologists and those not specialized in neuropathology, leading to misinterpretations and wrong diagnoses. Alternatively, changes may mask underlying neuropathological processes. “Specialized structures” comprising the hippocampus and the circumventricular organs, including the vascular organ of the lamina terminalis, subfornical organ, subcommissural organ, pineal gland, median eminence/neurohypophyseal complex, choroid plexus, and area postrema, are displayed. Unusual cell types, including cerebellar external germinal cells, CNS progenitor cells, and Kolmer cells, are presented. In addition, some newly recognized cell types as of yet incompletely understood significance and functionality, such as synantocytes and aldynoglia, are introduced and described. Unusual reactive astrocytes in cats, central chromatolysis, neuronal vacuolation, spheroids, spongiosis, satellitosis, melanosis, neuromelanin, lipofuscin, polyglucosan bodies, and psammoma bodies may represent incidental findings of uncertain or no significance and should not be confused with significant microscopic changes. Auto- and heterolysis as well as handling and histotechnological processing may cause postmortem morphological changes of the CNS, including vacuolization, cerebellar conglutination, dark neurons, Buscaino bodies, freezing, and shrinkage artifacts, all of which have to be differentiated from genuine lesions. Postmortem invasion of micro-organisms should not be confused with intravital infections. Awareness of these different changes and their recognition are a prerequisite for identifying genuine lesions and may help to formulate a professional morphological and etiological diagnosis.

scholarly journals Genetic models to study adult neurogenesis.

2005 ◽  
Vol 52 (2) ◽  
pp. 359-372 ◽  
Author(s):  
Robert K Filipkowski ◽  
Anna Kiryk ◽  
Anna Kowalczyk ◽  
Leszek Kaczmarek
Keyword(s):  
Nitric Oxide ◽  
Central Nervous System ◽  
Nervous System ◽  
Transcription Factors ◽  
Growth Factors ◽  
Olfactory Bulb ◽  
Adult Neurogenesis ◽  
Knock Out ◽  
Associated Proteins ◽  
The Central Nervous System

In the central nervous system (CNS) generation of new neurons continues throughout adulthood, when it is limited to the olfactory bulb and hippocampus. The knowledge regarding the function of newly-generated neurons remains limited and is vigorously investigated using diverse approaches. Among these are genetically modified mice, most of them of knock-out type (KO). Results from 23 diverse KO mouse models demonstrate the importance of particular proteins (growth factors, nitric oxide synthases, receptors, cyclins/cyclin-associated proteins, transcription factors, etc.) in adult neurogenesis (ANGE) as well as separate it from developmental neurogenesis. These results bring us closer to revealing the function of newly generated neurons in adult brains.

Lumbosacral vertebral compression syndrome

1980 ◽  
Vol 61 (4) ◽  
pp. 42-46
Author(s):  
H. M. Shulman ◽  
N. P. Popov
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Lumbar Spine ◽  
Clinical Picture ◽  
Morphological Study ◽  
Morphological Changes ◽  
Compression Syndrome ◽  
Neuromuscular Apparatus ◽  
The Central Nervous System ◽  
Spinal Roots

The clinical picture of the lesion and the results of a morphological study of a patient with osteochondrosis of the lumbar spine with compression of the spinal roots are described. Morphological changes of a degenerative-dystrophic nature were found not only in the formations located in the compression focus, but also in the peripheral neuromuscular apparatus, segmental and suprasegmental structures of the central nervous system.

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