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Myelinated Nerves (myelinated + nerve)

Distribution by Scientific Domains
Medical Sciences60%
Life Sciences40%

Terms modified by Myelinated Nerves

  • myelinated nerve fiber
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    Selected Abstracts

    Development of the Schwann cell lineage: From the neural crest to the myelinated nerve

    GLIA, Issue 14 2008
    Ashwin Woodhoo
    Abstract The myelinating and nonmyelinating Schwann cells in peripheral nerves are derived from the neural crest, which is a transient and multipotent embryonic structure that also generates the other main glial subtypes of the peripheral nervous system (PNS). Schwann cell development occurs through a series of transitional embryonic and postnatal phases, which are tightly regulated by a number of signals. During the early embryonic phases, neural crest cells are specified to give rise to Schwann cell precursors, which represent the first transitional stage in the Schwann cell lineage, and these then generate the immature Schwann cells. At birth, the immature Schwann cells differentiate into either the myelinating or nonmyelinating Schwann cells that populate the mature nerve trunks. In this review, we will discuss the biology of the transitional stages in embryonic and early postnatal Schwann cell development, including the phenotypic differences between them and the recently identified signaling pathways, which control their differentiation and maintenance. In addition, the role and importance of the microenvironment in which glial differentiation takes place will be discussed. © 2008 Wiley-Liss, Inc. [source]

    Herpetic Cytopathic Features Confined to Folliculosebaceous Units: What does it Mean?

    JOURNAL OF CUTANEOUS PATHOLOGY, Issue 1 2005
    N Walsh
    The histopathological changes of herpes simplex, zoster and varicella are considered to be indistinguishable from one another. The clinical setting with adjunctive studies generally clarifies the diagnosis. Vesicular lesions in all 3 conditions can involve epidermal and adnexal epithelium with characteristic cytopathic features. We describe 3 patients with non-vesicular eruptions on the head and neck whose biopsies revealed exclusive folliculosebaceous involvement by herpes. All three patients developed typical herpes zoster within days of the biopsy. There is compelling scientific evidence in the literature indicating that, in herpes zoster, the virus is transported from dorsal root or trigeminal ganglia via myelinated nerves to the skin. These terminate at the isthmus of hair follicles and primary infection of follicular and sebaceous epithelium occurs. Secondary spread of infection to the epidermis follows. In contrast, data pertaining to recurrent herpes simplex indicates that axonal transport of the virus from sensory ganglia to the skin is directed primarily to the epidermis, via terminal non-myelinated nerve twigs. The clinical evolution of our 3 cases and scientific data in the literature indicate that exclusive folliculosebaceous involvement by herpes, in the setting of a non-vesicular eruption, represents early herpes zoster. [source]

    Disposition of axonal caspr with respect to glial cell membranes: Implications for the process of myelination

    JOURNAL OF NEUROSCIENCE RESEARCH, Issue 15 2009
    Liliana Pedraza
    Abstract Neurofascin-155 (NF155) and caspr are transmembrane proteins found at discrete locations early during development of the nervous system. NF155 is present in the oligodendrocyte cell body and processes, whereas caspr is on the axonal surface. In mature nerves, these proteins are clustered at paranodes, flanking the node of Ranvier. To understand how NF155 and caspr become localized to the paranodal regions of myelinated nerves, we have studied their distribution over time in myelinating cultures. Our observations indicate that these two proteins are recruited to the cell surface at the contact zone between axons and oligodendrocytes, where they trans-interact. This association explains the early pattern of caspr distribution, a helical coil that winds around the axon, resembling the turns of the myelin sheath. Caspr, an axonal membrane protein, therefore seems to move in register with the overlying myelinating cell via its interactions with myelin proteins. We suggest that NF155 is the glial cell membrane protein responsible for caspr distribution. The pair act as interacting partners on either side of the axoglial contact area. Most likely, there are other proteins on the axonal surface whose distribution is equally influenced by interaction with the nascent myelin sheath. The fact that caspr follows the movement of the spiraling membrane has a direct affect on the interpretation of the way in which myelin is formed. © 2009 Wiley-Liss, Inc. [source]

    Opportunities afforded by the study of unmyelinated nerves in skin and other organs

    MUSCLE AND NERVE, Issue 6 2004
    William R. Kennedy MS
    Abstract Neurological practice is mainly focused on signs and symptoms of disorders that involve functions governed by myelinated nerves. Functions controlled by unmyelinated nerve fibers have necessarily remained in the background because of the inability to consistently stain, image, or construct clinically applicable neurophysiological tests of these nerves. The situation has changed with the introduction of immunohistochemical methods and confocal microscopy into clinical medicine, as these provide clear images of thin unmyelinated nerves in most organs. One obvious sign of change is the increasing number of reports from several laboratories of the pathological alterations of cutaneous nerves in skin biopsies from patients with a variety of clinical conditions. This study reviews recent methods to stain and image unmyelinated nerves as well as the use of these methods for diagnosing peripheral neuropathy, for experimental studies of denervation and reinnervation in human subjects, and for demonstrating the vast array of unmyelinated nerves in internal organs. The new ability to examine the great variety of nerves in different organs opens opportunities and creates challenges and responsibilities for neurologists and neuroscientists. Muscle Nerve 756,767, 2004 [source]

    Morphologic, functional and behavioral effects of titanium dioxide exposure on nerves

    CLINICAL ORAL IMPLANTS RESEARCH, Issue 5 2004
    An experimental study on rats
    Abstract Objectives: The purpose of this study was to explore morphologic, functional, and behavioral effects of titanium dioxide (TiO2) on nerves. Material and methods: A total of 17 albino rats were used for nerve conduction experiments, hot-plate tests, and histological evaluation. TiO2 was implanted unilaterally on the sciatic nerves of five rats. Ten days after surgery, test and control nerves were dissected and their signal transduction speeds were quantified by suction electrodes in a bath containing a Tyrode solution. Twelve rats were divided into three equal groups resulting in equal number of nerves (n=8) for TiO2 implantation, surgical exposure of the nerves, and for use as controls. One week after surgery, hot-plate tests were undertaken for 10 consecutive days to determine response latencies of the nerves. At the termination of the experiments, the nerves were harvested, processed, and examined under a microscope. Results: The signal transduction speeds of TiO2 -implanted nerves was similar to control specimens (P>0.05). The avoidance responses of TiO2 -implanted, surgically exposed, and control nerves were comparable (P>0.05). At the cellular level, TiO2 did not lead to any signs of adverse reactions on nerves. Conclusions: TiO2, the main oxide surrounding endosseous titanium implants, does not alter the structure and the function of myelinated nerves. Résumé Le but de cette étude a été d'explorer les effets morphologiques, du comportement, de la fonction du dioxide de titane (TiO2) sur les nerfs. Dix-sept rats albinos ont été utilisés pour ces expériences de comportement nerveux, des tests en culture et l'évaluation histologique. Le TiO2 a été implanté unilatéralement sur les nerfs sciatiques de cinq rats. Dix jours après la chirurgie, les nerfs tests et contrôles ont été disséqués et leur vitesse de transduction du signal ont été quantifiée par des électrodes de succion dans un bain contenant une solution de thyrode. Douze rats ont été répartis en trois groupes égaux résultant en un nombre égal de nerfs (n=8) pour l'implantation de TiO2, l'exposition chirurgicale des nerfs et pour l'utilisation comme contrôle. Une semaine après la chirurgie, des tests de culture ont été effectués durant dix jours d'affilée pour déterminer les temps de latence de réponse des nerfs. A la fin des expériences, les nerfs ont été prélevés et examinés sous microscope. Les vitesses de transduction du signal des nerfs où il y avait implantation de TiO2 étaient semblables aux contrôles (P>0.05). Les réponses de manquement des nerfs contrôles, chirurgicalement exposés et implantés TiO2 étaient semblables (P>0.05). Au niveau cellulaire, le TiO2 n'entraînait pas d'effets secondaires sur les nerfs. Le dioxyde de titane, l'oxyde principal entourant les implants titane endoosseux n'altère ni la structure ni la fonction des nerfs myélinisés. Zusammenfassung Ziel: Es war das Ziel dieser Studie, morphologische und funktionelle Verhaltensänderungen eines Nerven als direkte Reaktion auf Titandioxid (TiO2) zu untersuchen. Material und Methode: Man verwendete für Versuche bezüglich Reizleitung der Nerven, für den Kochplattentest und für histologische Untersuchungen insgesamt 17 Albinoratten. Zuerst implantierte man bei fünf Ratten einseitig TiO2 direkt auf den Ischiasnerven. 10 Tage nach der Chirurgie resezierte man die Test- und die Kontrollnerven, legte sie in ein Bad mit Tyrodelösung und mass mit Saugelektroden die Leitgeschwindigkeit eines Signals. Die 12 übrigen Ratten teilte man auf drei gleichgrosse Gruppen auf und erhielt somit je acht Nerven (n=8) für die Implantation von TiO2, die chirugische Entblössung oder für die Kontrollgruppe. Eine Woche nach der Chirurgie führte man an 10 aufeinanderfolgenden Tagen den Kochplattentest durch, um Verzögerungen der Nervenreaktion zu messen. Nach Abschluss dieser Untersuchung entnahm man die Nerven, bereitete sie histologisch auf und untersuchte sie anschliessend unter dem Mikroskop. Resultate: Die Leitgeschwindigkeit eines Signals beim Nerven mit implantiertem TiO2 war ganz ähnlich wie bei den Kontrollnerven (P>0.05). Die Abwehrreaktion von Nerven mit implantiertem TiO2, von chirurgisch entblössten Nerven und von Kontrollnerven war vergleichbar (P>0.05). Auf zellulärer Ebene führte TiO2 zu keiner Abwehrreaktion der Nerven. Zusammenfassung: Titandioxid, anteilsmässig das häufigste Oxid auf enossalen Implantaten, verändert weder Struktur noch Funktion von myelinisierten Nerven. Resumen Objetivos: El propósito de este estudio fue explorar los efectos morfológicos, funcionales y de comportamiento del dióxido de titanio (TiO2) sobre los nervios. Material y métodos: Se usaron un total de 17 ratas albinas para experimentos de conducción nerviosa, pruebas de plato caliente, y evaluación histológica. Se implantó TiO2 unilateralmente en los nervios ciáticos de cinco ratas. 10 días tras la cirugía, se disecaron los nervios de prueba y de control y se cuantificaron sus velocidades de transducción de señales por electrodos de succión en un baño conteniendo solución tiroidea. Se dividió a 12 ratas en tres grupos iguales resultando en igual numero de nervios (n=8) para implantación de TiO2, exposición quirúrgica de los nervios y para usarlos de control. Una semana tras la cirugía, se llevaron a cabo pruebas de plato caliente durante 10 días consecutivos para determinar las latencias de respuesta de los nervios. A la terminación de los experimentos, los nervios se recolectaron, se procesaron y se examinaron bajo el microscopio. Resultados: Las velocidades de transducción de señales de los nervios implantados de TiO2 fueron similares a las de los especímenes de control (P>0.05). Las respuestas de huida de los nervios implantados de TiO2, expuestos quirúrgicamente, y los nervios de control fueron comparables (P>0.05). A nivel celular, el TiO2 no condujo a ningún signo de reacciones adversas en los nervios. Conclusiones: El dióxido de titanio, el óxido principal que rodea a los implantes endoóseos de titanio, no altera la estructura ni la función de los nervios mielínicos. [source]