scholarly journals The Science and Art of Nerve Fiber Teasing for Myelinated Nerves: Methodology and Interpretation

2019 ◽  
Vol 48 (1) ◽  
pp. 49-58 ◽  
Author(s):  
Brad Bolon ◽  
Ingrid D. Pardo ◽  
Georg J. Krinke
Keyword(s):  
Nerve Fiber ◽  
Viscous Medium ◽  
Nerve Fibers ◽  
Laboratory Research ◽  
Myelinated Nerve ◽  
Toxicity Studies ◽  
Science And Art ◽  
Animal Toxicity ◽  
Myelinated Nerves ◽  
Coated Glass Slide

Nerve fiber teasing is a sensitive technique utilized in diagnostic neuropathology practice, laboratory research, and animal toxicity studies for characterizing changes in single myelinated nerve fibers over extended distances. In animal toxicity studies, a nerve portion (approximately 10 mm in length) is stained with Sudan black for 24 to 48 hours and then transferred into a drop of viscous medium (eg, glycerin) mounted on an adhesive-coated glass slide, positioning it such that the proximodistal orientation is known. Individual fibers are removed using fine forceps while the sample is viewed under a stereomicroscope. In general, lesions can be identified during teasing, but more detailed characterization and photodocumentation is undertaken once nerve fibers have been dried and coverslipped. Nerve fiber teasing is particularly useful for distinguishing early stages of axonal degeneration (which presents as ovoid fiber fragments in the midinternodal region) from segmental demyelination (which presents as loss of original myelin segments and their replacement by thinner, shorter segments in the absence of axonal damage). The slow, laborious nature of nerve fiber teasing dictates that the technique will be employed on a few samples as an auxiliary method to better define the pathogenesis of nerve lesions first identified by conventional histopathologic assessment.

scholarly journals CONTINUOUS CONDUCTION OF IMPULSES IN PERIPHERAL MYELINATED NERVE FIBERS

1951 ◽  
Vol 35 (2) ◽  
pp. 343-360 ◽  
Author(s):  
Y. Laporte
Keyword(s):  
Nerve Fiber ◽  
Continuous Process ◽  
Conduction Block ◽  
Nerve Fibers ◽  
Nerve Trunk ◽  
Conduction Time ◽  
Myelinated Nerve ◽  
Myelinated Nerve Fibers ◽  
Single Nerve ◽  
Internodal Segment

1. Conduction of impulses in peripheral myelinated fibers of a nerve trunk is a continuous process, since with uninjured nerve fibers: (a) within each internodal segment the conduction time increases continuously and linearly with increasing conduction distance; (b) the presence of nodes of Ranvier does not result in any detectable discontinuity in the conduction of the impulse; (c) the ascending phase of the spike always has an S shape and never presents signs of fractionation; (d) the shape and magnitude of the spike are constant at all points of each internodal segment. 2. Records have been presented of the external logitudinal current that flows during propagation of an impulse in undissected single nerve fiber (Fig. 6). 3. Propagation of impulses across a conduction block occurs with a readily demonstrable discontinuity.

Unusual particle trajectories and structural arrangements in myelinated nerve fibers

1979 ◽  
Vol 57 (10) ◽  
pp. 1182-1186 ◽  
Author(s):  
Richard S. Smith ◽  
Keith D. McLeod
Keyword(s):  
Endoplasmic Reticulum ◽  
Xenopus Laevis ◽  
Nerve Fiber ◽  
Particle Motion ◽  
Axial Direction ◽  
Nerve Fibers ◽  
Myelinated Axons ◽  
Rare Type ◽  
Myelinated Nerve ◽  
Myelinated Nerve Fibers

Others have reported that axonally transported particles, which usually travel in a direction roughly parallel to the axis of the nerve fiber, may suddenly shift sideways as though changing tracks. Examples of this rare type of movement are shown for particles undergoing transport in myelinated axons of Xenopus laevis. An examination of the structure of axons from Xenopus showed that some microtubules, neurofilaments, and elements of endoplasmic reticulum may also exhibit marked deviations from the axial direction. It is concluded that it is not necessary to propose any mechanism for changing tracks in order to explain the particle motion.

Peripheral Nerve Injection Injury

Neurosurgery ◽  
1979 ◽  
Vol 4 (3) ◽  
pp. 244-253 ◽  
Author(s):  
Fred Gentili ◽  
Alan Hudson ◽  
David G. Kline ◽  
Dan Hunter
Keyword(s):  
Nerve Fiber ◽  
Nerve Injury ◽  
Light And Electron Microscopy ◽  
Nerve Fibers ◽  
Myelinated Nerve ◽  
Injection Injury ◽  
Nerve Fascicle ◽  
Minimal Damage ◽  
Sciatic Nerves ◽  
Subsequent Regeneration

Abstract In an attempt to answer questions regarding nerve injection injuries, we injected 11 agents in current use and commonly administered by intramuscular injection into the sciatic nerves of adult Wistar rats. Equal volumes of normal saline were used as control. We harvested the sciatic nerves at various times after injection and examined them by both light and electron microscopy. We performed myelinated nerve fiber counts and constructed histograms. Any impairment of motor function was also noted. We gave injections to 79 animals a total of 158 times; 116 injections were directly into the nerve fascicle (intrafascicular) and 42 were into the epineural tissue (extrafascicular). The results revealed considerable variation in the degree of nerve fiber injury according to the agent injected. Minimal damage resulted from the injection of irondextran. meperidine, and cephalothin, and maximal nerve injury followed the injection of penicillin, diazepam, and chlorpromazine. The site of injection was crucial. Intrafascicular injection was invariably associated with severe nerve injury, but, with few exceptions, extrafascicular injection resulted in minimal damage. The quantity of drug injected was also important in determining the degree of injury. Large, heavily myelinated fibers were more susceptible to injection injury than smaller, thinly myelinated nerve fibers. The effect of the injected drug seemed to be related to injury of the nerve fiber unit—both the axon and the Schwann cell with its myelin sheath. Regeneration in damaged nerves was a constant finding; even the most severely injured nerves, with total axonal degeneration, underwent subsequent regeneration.

scholarly journals STUDIES ON THE PROBLEM OF PRESERVATION OF MYELIN SHEATH ULTRASTRUCTURE: EVALUATION OF FIXATION, DEHYDRATION, AND EMBEDDING TECHNIQUES

1961 ◽  
Vol 9 (2) ◽  
pp. 429-443 ◽  
Author(s):  
Richard M. Condie ◽  
A. Ervin Howell ◽  
Robert A. Good
Keyword(s):  
Electron Microscopy ◽  
Myelin Sheath ◽  
Nerve Fibers ◽  
Nerve Tissue ◽  
Tissue Preparation ◽  
Myelinated Nerve ◽  
Myelinated Nerve Fibers ◽  
Fixation Techniques ◽  
Myelinated Nerves ◽  
Embedding Methods

Currently accepted methods of tissue preparation for electron microscopy result in alterations of myelinated nerve fibers. In an attempt to minimize distortion of myelin, various fixation techniques, dehydration schedules, and embedding methods have been evaluated. It was found that the major damage to myelinated nerves occurs in the embedding procedure. A technique for embedding nerve tissue using the polyester Vestopal W is described which was found to result in improved preservation of myelin.

HISTOMETRIC AND ULTRASTRUCTURAL ORGANIZATION OF THE NERVIMUSCULAR TERMINALS OF SKELETAL MUSCLES AT A HYPOKINESIA

2019 ◽  
pp. 55-63
Author(s):  
Z. M. Yaschyshyn ◽  
S. L. Popel
Keyword(s):  
Skeletal Muscles ◽  
Structural Adjustment ◽  
Muscle Fibers ◽  
Electron Microscopic Examination ◽  
Nerve Fibers ◽  
Ultrastructural Changes ◽  
Ultrastructural Organization ◽  
Electron Microscopic ◽  
Myelinated Nerve ◽  
Male Wistar Rats

The aim: to study the dynamics of histological and ultrastructural changes in muscle fibers and their neuromuscular endings under conditions of prolonged hypokinesia at different stages of ontogenesis. Methods. Studied skeletal muscles and their peripheral nervous apparatus of laboratory male Wistar rats aged 30 to 270 days. The restriction of motor activity was carried out in special canister cells for 30, 60, 90, and 240 days (5 animals for each term). To determine the type of muscle fiber, the Nahlas histochemical method was used, the Kulchitsky method was used to detect myelinated nerve fibers, the Bilshovsky-Gros method and the electron microscopic method to identify neuromuscular endings. Results. The data of histological and electron microscopic examination of skeletal muscle fibers and their neuromuscular endings under conditions of prolonged hypokinesia indicate their regular restructuring during the development of muscles, the formation of their synapses and structures that are associated with them at different stages of ontogenesis. Conclusion. The study provides an in-depth understanding of the relative frequency and nature of the disturbance of the neuromuscular endings during prolonged hypokinesia and its effect on the dynamics of structural adjustment of individual types of muscle fibers in ontogenesis.

HISTOMETRIC AND ULTRASTRUCTURAL ORGANIZATION OF THE NERVIMUSCULAR TERMINALS OF SKELETAL MUSCLES AT A HYPOKINESIA

2019 ◽  
pp. 55-63
Author(s):  
Z. M. Yaschyshyn ◽  
S. L. Popel
Keyword(s):  
Skeletal Muscles ◽  
Structural Adjustment ◽  
Muscle Fibers ◽  
Electron Microscopic Examination ◽  
Nerve Fibers ◽  
Ultrastructural Changes ◽  
Ultrastructural Organization ◽  
Electron Microscopic ◽  
Myelinated Nerve ◽  
Male Wistar Rats

The aim: to study the dynamics of histological and ultrastructural changes in muscle fibers and their neuromuscular endings under conditions of prolonged hypokinesia at different stages of ontogenesis. Methods. Studied skeletal muscles and their peripheral nervous apparatus of laboratory male Wistar rats aged 30 to 270 days. The restriction of motor activity was carried out in special canister cells for 30, 60, 90, and 240 days (5 animals for each term). To determine the type of muscle fiber, the Nahlas histochemical method was used, the Kulchitsky method was used to detect myelinated nerve fibers, the Bilshovsky-Gros method and the electron microscopic method to identify neuromuscular endings. Results. The data of histological and electron microscopic examination of skeletal muscle fibers and their neuromuscular endings under conditions of prolonged hypokinesia indicate their regular restructuring during the development of muscles, the formation of their synapses and structures that are associated with them at different stages of ontogenesis. Conclusion. The study provides an in-depth understanding of the relative frequency and nature of the disturbance of the neuromuscular endings during prolonged hypokinesia and its effect on the dynamics of structural adjustment of individual types of muscle fibers in ontogenesis.

scholarly journals Sex-related differences in response to masseteric injections of glutamate and nerve growth factor in healthy human participants

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abdelrahman M. Alhilou ◽  
Akiko Shimada ◽  
Camilla I. Svensson ◽  
Peter Svensson ◽  
Malin Ernberg ◽  
...  
Keyword(s):  
Nmda Receptors ◽  
Nerve Fiber ◽  
Masseter Muscle ◽  
Pain Sensitivity ◽  
Nerve Fibers ◽  
Receptor Expression ◽  
Healthy Human ◽  
Neurophysiological Mechanisms ◽  
Human Participants ◽  
Positive Correlations

AbstractThe neurophysiological mechanisms underlying NGF-induced masseter muscle sensitization and sex-related differences in its effect are not well understood in humans. Therefore, this longitudinal cohort study aimed to investigate the effect of NGF injection on the density and expression of substance P, NMDA-receptors and NGF by the nerve fibers in the human masseter muscle, to correlate expression with pain characteristics, and to determine any possible sex-related differences in these effects of NGF. The magnitude of NGF-induced mechanical sensitization and pain during oral function was significantly greater in women than in men (P < 0.050). Significant positive correlations were found between nerve fiber expression of NMDA-receptors and peak pain intensity (rs = 0.620, P = 0.048), and expression of NMDA-receptors by putative nociceptors and change in temporal summation pain after glutamate injection (rs = 0.561, P = 0.003). In women, there was a significant inverse relationship between the degree of NGF-induced mechanical sensitization and the change in nerve fiber expression of NMDA-receptors alone (rs = − 0.659, P = 0.013), and in combination with NGF (rs = − 0.764, P = 0.001). In conclusion, women displayed a greater magnitude of NGF-induced mechanical sensitization that also was associated with nerve fibers expression of NMDA-receptors, when compared to men. The present findings suggest that, in women, increased peripheral NMDA-receptor expression could be associated with masseter muscle pain sensitivity.

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