-
The Journal of General Physiology Mar 1956Cross sections of olfactory nerves present a unique appearance. They indicate the presence of large numbers of very small nerve fibers, with a modal diameter of about...
Cross sections of olfactory nerves present a unique appearance. They indicate the presence of large numbers of very small nerve fibers, with a modal diameter of about 0.2 micro and a narrow range for their size variation. From one side of the nasal septum of a pig the yield of fibers was estimated at 6,000,000; the number arising from the turbinates would be considerably larger. The fibers are attached to the membranes of the Schwann sheaths in large bundles through mesaxons longer and more branched than those that have been seen in other nerves. Continuity of the axons between the nerves and the bipolar cells was traced in an examination of the olfactory mucous membrane; and the indication of a one-to-one relationship between cells and axons was reinforced by a comparative count. After the axons leave the bipolar cells they become incased in the central projections of the sustentacular cells. Where the latter come into contact with the basal cells the axons emerge to push back the plasma membranes of the basal cells in the first step in acquiring their nerve sheaths. Later steps are described. When the axons are delivered by the basal cells to the collecting Schwann tubes, they are already aggregated into small bundles with sheaths fundamentally the same as those they will possess until they are delivered to the glia in the olfactory bulb. Some of the aspects of the cytology of the bipolar cells and adjoining sustentacular cells are described. A survey of the physiological properties of olfactory nerve fibers was made in some experiments on the olfactory nerve of the pike. Almost all of the action potential is encompassed within a single elevation, manifesting at its front a conduction velocity of 0.2 m./sec. For a comparison, the last elevation in the C action potential in the sciatic nerve of the frog is cited as an example of conduction at the same velocity. Though expressed through long time constants, the properties of the pike olfactory fibers conform to the generalized schema for properties of vertebrate nerve fibers. This conformity signalizes that they differ from the exceptional properties of the unmedullated fibers of dorsal root origin. An afferent function for unmedullated nerve fibers does not imply that the fibers concerned are alike in their physiological properties.
Topics: Action Potentials; Animals; Axons; Ganglia, Spinal; Neuroglia; Neurons; Olfactory Nerve; Smell; Swine
PubMed: 13295549
DOI: 10.1085/jgp.39.4.473 -
Chemical Senses Sep 2009To investigate factors that influence the degree of neural regeneration and recovery, we studied 2 olfactory nerve injury models. Transection of the olfactory nerves...
To investigate factors that influence the degree of neural regeneration and recovery, we studied 2 olfactory nerve injury models. Transection of the olfactory nerves along the surface of the olfactory bulb was performed in OMP-tau-lacZ mice using either a flexible Teflon blade (mild injury) or a stainless steel blade (severe injury). Histological assessment of recovery within the olfactory bulb was made at 5, 14, and 42 days after injury. We used X-gal staining to label the degenerating and regenerating olfactory nerve fibers and immunohistochemical staining to detect the presence of reactive astrocytes and macrophages. Areas of injury-associated tissue were significantly smaller in the mild injury model, and at 42 days, the regenerated nerves had reestablished connections to the glomerular layer of the bulb. With severe injury, there were larger areas of injury-associated tissue, more astrocytes and macrophages, and a decrease in regenerated nerve fibers. When dexamethasone (DXM) was injected after severe injury, there was a significant reduction in injury-associated tissue, better nerve recovery, and fewer astrocytes and macrophages. These results demonstrate that recovery in the olfactory system varies with the severity of injury and that DXM treatment may have therapeutic value by reducing injury-associated tissue and improving recovery outcome.
Topics: Animals; Anti-Inflammatory Agents; Dexamethasone; Mice; Mice, Transgenic; Nerve Regeneration; Olfactory Bulb; Olfactory Nerve; Olfactory Nerve Injuries
PubMed: 19578153
DOI: 10.1093/chemse/bjp038 -
Anatomical Record (Hoboken, N.J. : 2007) Sep 2013The mammalian olfactory bulb (OB) has all the features of a whole mammalian brain but in a more reduced space: neuronal lamination, sensory inputs, afferences, or... (Review)
Review
The mammalian olfactory bulb (OB) has all the features of a whole mammalian brain but in a more reduced space: neuronal lamination, sensory inputs, afferences, or efferences to other centers of the central nervous system, or a contribution of new neural elements. Therefore, it is widely considered as "a brain inside the brain." Although this rostral region has the same origin and general layering as the other cerebral cortices, some distinctive features make it very profitable in experimentation in neurobiology: the sensory inputs are driven directly on its surface, the main output can be accessed anatomically, and new elements appear in it throughout adult life. These three morphological characteristics have been manipulated to analyze further the response of the whole OB. The present review offers a general outlook into the consequences of such experimentation in the anatomy, connectivity and neurochemistry of the OB after (a) sensory deprivation, mainly by naris occlusion; (b) olfactory deinnervation by means of olfactory epithelium damage, olfactory nerve interruption, or even olfactory tract disruption; (c) the removal of the principal neurons of the OB; and (d) management of the arrival of newborn interneurons from the rostral migratory stream. These experiments were performed using surgical or chemical methods, but also by means of the analysis of genetic models, some of whose olfactory components are missing, colorless or mismatching within the wild-type scenario of odor processing.
Topics: Adaptation, Physiological; Animals; Cell Differentiation; Cell Proliferation; Humans; Interneurons; Nerve Net; Neurogenesis; Neurons; Odorants; Olfaction Disorders; Olfactory Bulb; Olfactory Perception; Sensory Deprivation; Signal Transduction; Smell
PubMed: 23904144
DOI: 10.1002/ar.22748 -
Anatomical Record (Hoboken, N.J. : 2007) Jul 2008In the late Nineteenth Century, Santiago Ramón y Cajal was able to reproduce an exceptional illustration of the Olfactory Nerve pathway and its myriad of cells, by... (Review)
Review
In the late Nineteenth Century, Santiago Ramón y Cajal was able to reproduce an exceptional illustration of the Olfactory Nerve pathway and its myriad of cells, by using the Golgi Method. Dr. Cajal focused intense study on the histology of the nervous system and published a treatise on the olfactory nerve fibers and the distinct peripheral origin and central nervous system endpoint of this unique pathway. The original title of this work is "Origen y terminación de las fibras nerviosas olfatorias" published in 1890. As the original publication is in Spanish, here we provide an English translation allowing present-day English speakers to read these writings. Cajal followed the trajectory of the olfactory nerve fibers as they transitioned between the peripheral and central nervous system and was able to assert that these fibers were not continuous from the olfactory bulb to the bipolar cells that relinquish into the olfactory epithelium, but that the olfactory system was made up of various cell types each having distinct morphologies and functions. This may very well be the first definitive description of the olfactory receptor neurons and the first illustrations of the continuity of these cells throughout the olfactory pathway. These meticulous histological preparations were created by first using Camillo Golgi's potassium dichromate and silver nitrate impregnation method known as "reazione nera" or "black reaction," where nerve cells, nerve fibers, and neuroglia could be visualized. This study exhibits the structural and functional organization of the mammalian fila olfactoria as it was investigated in centuries past.
Topics: Animals; History, 19th Century; Nerve Fibers; Neurosciences; Olfactory Bulb; Olfactory Nerve; Olfactory Receptor Neurons; Spain; Staining and Labeling
PubMed: 18383279
DOI: 10.1002/ar.20660 -
Cells, Tissues, Organs 2012Previously, we introduced the biogenic conduit (BC) as a novel autologous nerve conduit for bridging peripheral nerve defects and tested its regenerative capacity in a... (Comparative Study)
Comparative Study
INTRODUCTION
Previously, we introduced the biogenic conduit (BC) as a novel autologous nerve conduit for bridging peripheral nerve defects and tested its regenerative capacity in a short- and long-term setting. The aim of the present study was to clarify whether intraluminal application of regeneration-promoting glial cells, including Schwann cells (SC) and olfactory ensheathing cells (OEC), displayed differential effects after sciatic nerve gap bridging.
MATERIAL AND METHODS
BCs were generated as previously described. The conduits filled with fibrin/SC (n = 8) and fibrin/OEC (n = 8) were compared to autologous nerve transplants (NT; n = 8) in the 15-mm sciatic nerve gap lesion model of the rat. The sciatic functional index was evaluated every 4 weeks. After 16 weeks, histological evaluation followed regarding nerve area, axon number, myelination index and N ratio.
RESULTS
Common to all groups was a continual improvement in motor function during the observation period. Recovery was significantly better after SC transplantation compared to OEC (p < 0.01). Both cell transplantation groups showed significantly worse function than the NT group (p < 0.01). Whereas nerve area and axon number were correlated to function, being significantly lowest in the OEC group (p < 0.001), both cell groups showed lowered myelination (p < 0.001) and lower N ratio compared to the NT group.
DISCUSSION
SC-filled BCs led to improved regeneration compared to OEC-filled BCs in a 15-mm-long nerve gap model of the rat.
Topics: Animals; Cell Culture Techniques; Female; Nerve Regeneration; Neuroglia; Olfactory Nerve; Peripheral Nerves; Rats; Rats, Inbred Lew; Schwann Cells; Transfection
PubMed: 22699447
DOI: 10.1159/000338059 -
Frontiers in Cellular and Infection... 2020can infect the brain and has been linked to late-onset dementia. , which infects mice, is often used to model human chlamydial infections. While it has been suggested...
can infect the brain and has been linked to late-onset dementia. , which infects mice, is often used to model human chlamydial infections. While it has been suggested to be also important for modelling brain infection, nervous system infection by has not been reported in the literature. has been shown to infect the olfactory bulb in mice after intranasal inoculation, and has therefore been suggested to invade the brain the olfactory nerve; however, nerve infection has not been shown to date. Another path by which certain bacteria can reach the brain is the trigeminal nerve, but it remains unknown whether species can infect this nerve. Other bacteria that can invade the brain the olfactory and/or trigeminal nerve can do so rapidly, however, whether spp. can reach the brain earlier than one-week post inoculation remains unknown. In the current study, we showed that can within 48 h invade the brain the olfactory nerve, in addition to infecting the trigeminal nerve. We also cultured the glial cells of the olfactory and trigeminal nerves and showed that readily infected the cells, constituting a possible cellular mechanism explaining how the bacteria can invade the nerves without being eliminated by glial immune functions. Further, we demonstrated that olfactory and trigeminal glia differed in their responses to , with olfactory glia showing less infection and stronger immune response than trigeminal glia.
Topics: Animals; Central Nervous System; Chlamydia Infections; Chlamydia muridarum; Mice; Neuroglia; Olfactory Nerve; Trigeminal Nerve
PubMed: 33489937
DOI: 10.3389/fcimb.2020.607779 -
PloS One Feb 2011Although the function of the adult olfactory system has been thoroughly studied, the molecular mechanisms regulating the initial formation of the olfactory nerve, the...
Although the function of the adult olfactory system has been thoroughly studied, the molecular mechanisms regulating the initial formation of the olfactory nerve, the first cranial nerve, remain poorly defined. Here, we provide evidence that both modulated Notch and bone morphogenetic protein (BMP) signaling affect the generation of neurons in the olfactory epithelium and reduce the number of migratory neurons, so called epithelioid cells. We show that this reduction of epithelial and migratory neurons is followed by a subsequent failure or complete absence of olfactory nerve formation. These data provide new insights into the early generation of neurons in the olfactory epithelium and the initial formation of the olfactory nerve tract. Our results present a novel mechanism in which BMP signals negatively affect Notch activity in a dominant manner in the olfactory epithelium, thereby regulating neurogenesis and explain why a balance of BMP and Notch activity is critical for the generation of neurons and proper development of the olfactory nerve.
Topics: Animals; Animals, Genetically Modified; Bone Morphogenetic Proteins; Cell Differentiation; Cell Movement; Cell Proliferation; Chick Embryo; Gene Expression Regulation, Developmental; Humans; Mice; Models, Biological; Neurogenesis; Olfactory Mucosa; Olfactory Nerve; Receptors, Notch; Signal Transduction
PubMed: 21383851
DOI: 10.1371/journal.pone.0017379 -
Frontiers in Neurology 2023Inverted papilloma (IP) and nasal polyp (NP), as two benign lesions, are difficult to distinguish on MRI imaging and clinically, especially in predicting whether the...
BACKGROUND AND PURPOSE
Inverted papilloma (IP) and nasal polyp (NP), as two benign lesions, are difficult to distinguish on MRI imaging and clinically, especially in predicting whether the olfactory nerve is damaged, which is an important aspect of treatment and prognosis. We plan to establish a new biomarker to distinguish IP and NP that may invade the olfactory nerve, and to analyze its diagnostic efficacy.
MATERIALS AND METHODS
A total of 74 cases of IP and 55 cases of NP were collected. A total of 80% of 129 patients were used as the training set (59 IP and 44 NP); the remaining were used as the testing set. As a multimodal study (two MRI sequences and clinical indicators), preoperative MR images including T2-weighted magnetic resonance imaging (T2-WI) and contrast-enhanced T1-weighted magnetic resonance imaging (CE-T1WI) were collected. Radiomic features were extracted from MR images. Then, the least absolute shrinkage and selection operator (LASSO) regression method was used to decrease the high degree of redundancy and irrelevance. Subsequently, the radiomics model is constructed by the rad scoring formula. The area under the curve (AUC), accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the model have been calculated. Finally, the decision curve analysis (DCA) is used to evaluate the clinical practicability of the model.
RESULTS
There were significant differences in age, nasal bleeding, and hyposmia between the two lesions ( < 0.05). In total, 1,906 radiomic features were extracted from T2-WI and CE-T1WI images. After feature selection, using 12 key features to bulid model. AUC, sensitivity, specificity, and accuracy on the testing cohort of the optimal model were, respectively, 0.9121, 0.828, 0.9091, and 0.899. AUC on the testing cohort of the optimal model was 0.9121; in addition, sensitivity, specificity, and accuracy were, respectively, 0.828, 0.9091, and 0.899.
CONCLUSION
A new biomarker combining multimodal MRI radiomics and clinical indicators can effectively distinguish between IP and NP that may invade the olfactory nerve, which can provide a valuable decision basis for individualized treatment.
PubMed: 37025198
DOI: 10.3389/fneur.2023.1151455 -
Surgery Journal (New York, N.Y.) Jul 2018Schwannomas are benign tumors, which arise from the Schwann cells of the central or peripheral nerves. They form 8% of all intracranial tumors and most of the cases...
Schwannomas are benign tumors, which arise from the Schwann cells of the central or peripheral nerves. They form 8% of all intracranial tumors and most of the cases arise from vestibular division of the 8 cranial nerve. Rare cases are shown to arise from the olfactory or optic nerve, being devoid of myelin sheath. Up to date and according to our best of knowledge, 66 cases have been reported till now. Here we present a review of the literature and a case report of a 56-year-old male with an accidently discovered anterior cranial fossa schwannoma, following a road traffic accident. Tumor was completely excised, using a right frontal approach. Histopathology revealed Antoni-A cellular pattern. Although rare, but olfactory nerve schwannomas should be included in the differential diagnosis in anterior cranial fossa space occupying lesions, and the approach should be designed taking into consideration, this rare entity.
PubMed: 30206542
DOI: 10.1055/s-0038-1669991