Detection of Organelles in Myelinated Nerve Fibers by Dark-Field Microscopy

1972 ◽  
Vol 50 (5) ◽  
pp. 467-469 ◽  
Author(s):  
R. S. Smith
Keyword(s):  
Optical Detection ◽  
Dark Field ◽  
Nerve Fibers ◽  
Spherical Particles ◽  
Axial Motion ◽  
Myelinated Nerve ◽  
Myelinated Nerve Fibers ◽  
Adult Rat ◽  
Dark Field Microscopy

Dark-field microscopy improves the optical detection of intraaxonal organelles. In living myelinated nerve fibers of the adult rat and the adult toad, fast (approximately 1 μm/s) somatopetal and somatofugal movement of near-spherical particles was seen. Rod-shaped organelles were also detected in nerve fibers from both the rat and the toad, but these organelles showed no axial motion.

Microtubule and Neurofilament Densities in Amphibian Spinal Root Nerve Fibers: Relationship to Axoplasmic Transport

1973 ◽  
Vol 51 (11) ◽  
pp. 798-806 ◽  
Author(s):  
Richard S. Smith
Keyword(s):  
Dorsal Root ◽  
Dark Field ◽  
Nerve Fibers ◽  
Axoplasmic Transport ◽  
Spinal Root ◽  
Myelinated Nerve ◽  
Dorsal Roots ◽  
Dark Field Microscopy ◽  
Spinal Roots ◽  
Ventral Roots

Dark-field microscopy of living myelinated nerve fibers from the spinal roots of Xenopus laevis revealed many spherical organelles moving in the axoplasm of fibers from the ventral roots and in fibers just distal to the dorsal root ganglion. Similar organelles were present but few were seen to move along fibers from the dorsal roots central to the ganglion. This observation prompted an ultrastructural study of microtubule and neurofilament densities in the myelinated fibers of the spinal roots. The density of microtubules was significantly less in fibers from the central part of the dorsal roots than in the rest of the spinal root system. Neurofilament densities were equivalent in all parts of the roots. Microtubules showed a significant association with mitochondria in the ventral roots and in the dorsal roots distal to the ganglion, but no significant association was obtained for the dorsal roots central to the ganglion. The meaning of these results in the axoplasmic transport of large organelles is discussed.

scholarly journals THE SUBMICROSCOPIC ORGANIZATION OF AXON MATERIAL ISOLATED FROM MYELIN NERVE FIBERS

1953 ◽  
Vol 98 (3) ◽  
pp. 269-276 ◽  
Author(s):  
E. De Robertis ◽  
C. M. Franchi
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Phase Contrast ◽  
Nerve Fibers ◽  
Myelinated Nerve ◽  
Myelinated Nerve Fibers ◽  
Dense Granules ◽  
Small Clusters ◽  
Membranous Material ◽  
The Way

A technique has been developed for the extrusion of axon material from myelinated nerve fibers. This material is then compressed and prepared for observation with the electron microscope. All the stages of preparation and purification of the axon material can be checked microscopically and in the present paper they are illustrated with phase contrast photomicrographs. Observation with the electron microscope of the compressed axons showed the presence of the following components: granules, fibrils, and a membranous material. Only the larger granules could be seen with the ordinary microscope. A considerable number of dense granules were observed. Of these the largest resemble typical mitochondria of 250 mµ by 900 mµ. In addition rows or small clusters of dense granules ranging in diameter from 250 to 90 mµ were present. In several specimens fragments of a membrane 120 to 140 A thick and intimately connected with the axon were found. The entire axon appeared to be constituted of a large bundle of parallel tightly packed fibrils among which the granules are interspersed. The fibrils are of indefinite length and generally smooth. They are rather labile structures, less resistant in the rat than in the toad nerve. They varied between 100 and 400 A in diameter and in some cases disintegrated into very fine filaments (less than 100 A thick). The significance is discussed of the submicroscopic structures revealed by electron microscopy of the material prepared in the way described.

scholarly journals A simplified empirical modeling of electrophysiological activity in a bundle of myelinated nerve fibers

2016 ◽  
Vol 14 (7) ◽  
pp. 3345-3350 ◽  
Author(s):  
Alvaro Gabriel Piza ◽  
Fernando Daniel Farfan ◽  
Ana Lia Albarracin ◽  
Facundo Adrian Lucianna ◽  
Jorge Humberto Soletta ◽  
...  
Keyword(s):  
Nerve Fibers ◽  
Empirical Modeling ◽  
Myelinated Nerve ◽  
Myelinated Nerve Fibers ◽  
Electrophysiological Activity

scholarly journals Myelin Basic Protein and Cardiac Sympathetic Neurodegeneration in Nonhuman Primates

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Jeanette M. Metzger ◽  
Helen N. Matsoff ◽  
Don Vu ◽  
Alexandra D. Zinnen ◽  
Kathryn M. Jones ◽  
...  
Keyword(s):  
Left Ventricle ◽  
Myelin Basic Protein ◽  
Basic Protein ◽  
Rhesus Macaques ◽  
Sympathetic Neurons ◽  
Nerve Fibers ◽  
Myelinated Nerve ◽  
Myelinated Nerve Fibers ◽  
Pparγ Agonist ◽  
Nerve Bundles

Minimal myelination is proposed to be a contributing factor to the preferential nigral neuronal loss in Parkinson’s disease (PD). Similar to nigral dopaminergic neurons, sympathetic neurons innervating the heart have long, thin axons which are unmyelinated or minimally myelinated. Interestingly, cardiac sympathetic loss in PD is heterogeneous across the heart, yet the spatial relationship between myelination and neurodegeneration is unknown. Here, we report the mapping of myelin basic protein (MBP) expression across the left ventricle of normal rhesus macaques (n = 5) and animals intoxicated with systemic 6-OHDA (50 mg/kg iv) to model parkinsonian cardiac neurodegeneration (n = 10). A subset of 6-OHDA-treated rhesus received daily dosing of pioglitazone (5 mg/kg po; n = 5), a PPARγ agonist with neuroprotective properties. In normal animals, MBP-immunoreactivity (-ir) was identified surrounding approximately 14% of axonal fibers within nerve bundles of the left ventricle, with more myelinated nerve fibers at the base level of the left ventricle than the apex p < 0.014 . Greater MBP-ir at the base was related to a greater number of nerve bundles at that level relative to the apex p < 0.05 , as the percent of myelinated nerve fibers in bundles was not significantly different between levels of the heart. Cardiac sympathetic loss following 6-OHDA was associated with decreased MBP-ir in cardiac nerve bundles, with the percent decrease of MBP-ir greater in the apex (84.5%) than the base (52.0%). Interestingly, cardiac regions and levels with more MBP-ir in normal animals showed attenuated sympathetic loss relative to areas with less MBP-ir in 6-OHDA + placebo (r = −0.7, p < 0.014 ), but not in 6-OHDA + pioglitazone (r = −0.1) subjects. Our results demonstrate that myelination is present around a minority of left ventricle nerve bundle fibers, is heterogeneously distributed in the heart of rhesus macaques, and has a complex relationship with cardiac sympathetic neurodegeneration and neuroprotection.

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