The author measured the severity of brain damage of 36 rabbits irradiated 2.45 GHz microwave for 10 minutes, 20 minutes and 30 minutes, respectively. Electromicroscopic and light microscopic findings of just after, 1 weeks, 2 weeks and 4 weeks after irradiated brain were compared in each time. Swelling and vacualization of nerve cell and mitochondria were noted. Also these changes tend to increased severity along amount of radiation, but revealed reversible changes with time. Myelinated and unmyelinated nerve fibers were examined as same manner. These nerve fibers also revealed swelling and vascuolization, these findings also tend to increase severity with irradiation power and more prominent at unmyelinated nerve fibers. Reversability of these findings after each time period were more prominent in myelinated nerve fibers than unmyelinated nerve fibers.
Brain ; Cerebrum* ; Microwaves* ; Mitochondria ; Myelin Sheath ; Nerve Fibers ; Nerve Fibers, Myelinated ; Nerve Fibers, Unmyelinated ; Neurons ; Rabbits*

An attempt has been made to discriminate synaptic diversity in the neostriatum of the cat with emphasis on the characteristic structures of axon terminals and postsynaptic profiles. The differentiation of the axon terminals was based on the size and shape of synaptic vesicles in the axoplasm. Three types of axon terminals could be differentiated: Type I, the terminals contained small round (45 nm in diameter) vesicles; type II, the terminals with large pleomorphic (50 nm) vesicles; and type III, the terminals contained flattened (45 x 25 nm) vesicles. The type I terminals were making asymmetrical or symmetrical synapses in contact with the somata, dendrites and dendritic spines of neurons in the neostriatum, and a few type I terminals making asymmetrical or symmetrical contact with axons were also observed. The type II and III terminals were making symmetrical contact with the somata and dendrites of neostriatal neurons. A few type II terminals formed at the node of Ranvier of myelinated nerve fibers were making symmetrical contact with large dendrites. Additionally, dendro-dendritic and serial syanpses were rarely found in the neostriatum. In the serial synapses composed of axo-dendritic and dendro-dendritic synapses, the type I terminals making asymmetrical contact and the type II making symmetrical contact were identified.
Animals ; Axons ; Cats* ; Dendrites ; Dendritic Spines ; Neostriatum* ; Nerve Fibers, Myelinated ; Neurons ; Presynaptic Terminals ; Synapses ; Synaptic Vesicles

Effects of aconitine on the retina and optic nerve were studied in rabbits by means of visual evoked potential(VEP), electroretinogram(ERG), and electron microscopy. Aconitine(0.4mg/kg) was administered intra peritoneally. The effects of aconitine were observed at 1 day, 3 days, 1 week, 2 weeks, 3 weeks, and 3 months after injection, respectively. The amplitude of VEP was decreased significantly at 1 and 2 weeks after injection. However ERG b-wave, c-wave, and the latency of VEP were not significantly changed during the experimental periods. Histopathological changes in the optic nerve and visual streak were characterized by disorganization of the lamellar structures of the myelin sheath, diffuse mitochondrial swelling, and vacuolization in the myelinated nerve fibers, which were increased in degree with time. No perceptible change in the retina including retinal pigment epithelium was observed in the experimental periods. Schwann cells and unmyelinated nerve fibers appeared unaffected, except for mild swelling of mitochondria. Above mentioned electrophysiological and electron microscopic studies indicated that the effect of aconitine on the rabbit eye was toxic myelo-optic neuropathy.
Aconitine* ; Microscopy, Electron ; Mitochondria ; Mitochondrial Swelling ; Myelin Sheath ; Nerve Fibers, Myelinated ; Nerve Fibers, Unmyelinated ; Optic Nerve ; Optic Nerve Diseases* ; Rabbits ; Retina ; Retinal Pigment Epithelium ; Schwann Cells

PURPOSE: We wanted to compare the nerve regeneration of inside-out vein grafts, muscle-filled inside-out vein grafts and fat-interposed inside-out vein grafts to repair the 10 mm sciatic nerve defects in rats. MATERIALS AND METHODS: We performed inside-out vein grafts, muscle-filled inside-out vein grafts and fat-interposed inside-out vein grafts to repair the 10 mm sciatic nerve defects in 45 rats. Histological examinations (the numbers and diameters of myelinated nerve fibers), electrophysiologic testing (Compound Muscle Action Potential (CMAP) and Nerve Conduction Velocity (NCV)) examinations were performed 3 months after surgery. RESULTS: Quantitative analysis of myelinated nerve fibers showed that total number of nerve fibers was significantly greater in group 1 or 3 than that in group 2. There were statistical differences in the three groups for the fiber diameters of the myelinated fibers. Electrophysiologic examination showed that both CMAP and NCV were significantly greater in group 3 than that in group 2 and there was no statistical difference between in groups 1 and 3. CONCLUSION: This study shows that fat-interposed inside-out vein grafts have excellent axonal regeneration as compared to that of inside-out vein grafts or muscle-filled inside-out vein grafts to repair 10 mm sciatic nerve defects in rat. Therefore fat-interposed inside-out vein grafts are an effective method to accelerate the early axonal regeneration for repairing nerve defects.
Action Potentials ; Animals ; Axons ; Muscles ; Myelin Sheath ; Nerve Fibers ; Nerve Fibers, Myelinated ; Nerve Regeneration ; Neural Conduction ; Rats ; Regeneration ; Sciatic Nerve ; Transplants ; Veins

Diabetic neuropathy is a broad term that encompasses many destructive syndromes that various kinds of neuronal population is affected in diabetes mellitus. Diabetic neuropathy has been postulated to occur by diverse pathogenetic mechanisms. Recent studies suggest that the reduction of neurotrophic factors is one of the causes of diabetic neuropathy. This study was performed to identify the effect of nerve growth factor on Schwann cell in the streptozotocin-induced diabetic rats morphologically. Sprague-Dawley rats (weighed about 200 gm) were rendered diabetes by injection of streptozotocin (STZ 65 mg/kg) and nerve growth factor was administered for 4 weeks. The result obtained are as followed: 1. Degenerations in cytoplasmic organelles of Schwann cell of the myelinated nerve fibers in diabetic rats were identified. 2. Degenerations in cytoplasmic organelles of the Schwann cell of the unmyelinated nerve fibers in diabetic rats were identified and abnormal axons were appeared. 3. Nerve growth factor had an effect on the recovery of degeneration and it was more effective in myelinated nerve fibers. These results suggest that early administration of nerve growth factor have the effect of protection of diabetic neuropathy by morphological study.
Animals ; Axons ; Cytoplasm ; Diabetes Mellitus ; Diabetic Neuropathies* ; Nerve Fibers, Myelinated ; Nerve Fibers, Unmyelinated ; Nerve Growth Factor* ; Nerve Growth Factors ; Neurons ; Organelles ; Rats* ; Rats, Sprague-Dawley ; Streptozocin

PURPOSE: To investigate the cellular changes and cellular characteristics of myelinated nerve fiber, unmyelinated nerve fiber and Schwann cell under the culture conditions of the explant of the long ciliary nerve. METHODS: The ciliary nerve was obtained from the eyecup after removal of the cornea and intraocular contents following the division of the eyeball at the limbal zone. The explant of the ciliary nerve was cultured with DMEM medium containing nerve growth factor in an incubator with a 5% CO2 atmosphere. The cultured ciliary nerve was examined with phase contrast microscopy at 35 days after culture and stained in the culture dish with 1% methylene blue. The cultured ciliary nerve was also examined with transmission electron microscope. RESULTS: The phase contrast microscopy showed monolayered Schwann cells and cells with thin cytoplasmic processes. The ultrastructure showed myelinated nerve fiber, unmyelinated nerve fiber and Schwann cells entrapped in the nerve fiber. The axoplasm of the myelinated nerve fiber showed the degeneration of microorganelles whereas the unmyelinated nerve fiber showed well preserved microorganelles such as neurofilaments and mitochondria within the axoplasm. CONCLUSIONS: These findings suggest that the axoplasm of the unmyelinated nerve fiber under these culture conditions is relatively better preserved than that of the myelinated nerve fiber probably due to the absence of the myelin sheath. Further study will be required to investigate whether the myelin sheath of the ciliary nerve derived from peripheral neuropathy may affect the functional change of the anterior segment of the eye.
Atmosphere ; Cornea ; Cytoplasm ; Incubators ; Methylene Blue ; Microscopy, Phase-Contrast ; Mitochondria ; Myelin Sheath ; Nerve Fibers ; Nerve Fibers, Myelinated ; Nerve Fibers, Unmyelinated ; Nerve Growth Factor ; Peripheral Nervous System Diseases ; Schwann Cells

A case of Isaacs syndrome with Trousseau s phenomenon wac studied electrophysiologically and histologically. The needle electromyography showed typical neuromyotonic discharges of spontaneous recurrent high-frequency(150-300Hz) bursts of motor unit activity with 0.5-3 second of duration and typical waning pattern This discharge was not suppressed by brachial plexus block Motor and sensory nerve conduction velocities were either s!ightly below or in the lower range of normal. In repetitive nerve stimulation test a decremental response to low rate stimulation was noted in abductor digiti quinti muscle. On sural nerve biopsy, there was a decrease in the number of myelinated nerve fibers showing both axonal and myelin degeneration The clinical and electrophysiologic abnormalities improved considerably after treatment with phenytoin.
Axons ; Biopsy ; Brachial Plexus ; Electromyography ; Isaacs Syndrome* ; Myelin Sheath ; Needles ; Nerve Fibers, Myelinated ; Neural Conduction ; Phenytoin ; Sural Nerve

PURPOSE: This study was performed to describe the ultrastructure of stromal nerve fibers in central, mid-peripheral, and peripheral parts of the human cornea by flat serial corneal section. METHODS: Seven samples from fresh normal cornea, derived from eyes with retinoblastoma and eyes from eye bank, were processed for transmission electron microscopic examinations. Flat serial sections reaching from mid-epithelium to the anterior stroma were observed. RESULTS: The myelinated and unmyelinated nerve fibers are alternately arranged and run parallel to the stromal collagen fibers at the periphery of the cornea. The main difference between the limbal and the central cornea is the presence of myelinated nerve fibers in the anterior peripheral stroma. The diameter of the unmyelinated nerve fiber measures between 0.25 and 0.63 micrometer in size. The corneal nerve fibers contain vesicles, mitochondria, and glycogen particles. The peripheral nerve fibers contain both clear and dense vesicles. The nerve fiber is separated by an interval of 0.3 micrometer from the cytoplasmic wall of keratocyte at the center of the cornea. CONCLUSIONS: The majority of the corneal nerve fibers can be classified as C-fibers due to their size. The presence of both clear and dense vesicles within the cytoplasm of the periphery of the cornea suggest that a small portion in the peripheral corneal nerve may be originated from the sympathetic nervous system. A close vicinity between the nerve fibers and keratocyte supports that nerve fibers might modulate the release of growth factors in the regulation of stromal and epithelial metabolism.
Collagen ; Cornea ; Cytoplasm ; Eye Banks ; Glycogen ; Humans ; Intercellular Signaling Peptides and Proteins ; Metabolism ; Mitochondria ; Myelin Sheath ; Nerve Fibers ; Nerve Fibers, Myelinated ; Nerve Fibers, Unmyelinated ; Peripheral Nerves ; Retinoblastoma ; Sympathetic Nervous System

Spinal Cord contusions in cats were produced experimentally by impact injuries to the surgically exposed cord at the second lumbar vertebral level. As a step in the investigation of the possible effect of spinal cord trauma on biochemical and ultrastructural changes in the injured cord, activities of lipid peroxidation were measured in the frozen-dried sample of the spinal cord and the fine structure of the myelinated nerve fiber in the white matter were observed before and after the cord injury. An increase of lipid peroxidation level was found as early as 30 minutes after the injury and the highest concentration was reached at 4 hours of injury. Fine structures of the myelinated nerve fibers were changed progressively with the lapse of time after the injury. By 1 hour after the contusion the myelinated nerve fibers showed moderately enlarged periaxonal space, attenuation and disarray of the myelin sheaths. By 4 hour after the contusion, there appeared disarray of the myelin sheaths, greatly enlarged periaxonal space and irregulary contoured axons. The effect of naloxone of the lipid peroxidation and fine ultrastructure of the myelinated nerve fibers were studied, and the results of this study suggested that naloxone have a beneficial effect on the change in lipid peroxidation and the preservation of the myelinated nerve fibers after injury.
Animals ; Axons ; Cats ; Contusions ; Lipid Peroxidation* ; Myelin Sheath* ; Naloxone* ; Nerve Fibers, Myelinated ; Spinal Cord Injuries ; Spinal Cord*

The purpose of this study was to determine the effect of treatment with thyrotropin releasing hormone(TRH) on the somatosensory evoked potentials(SSEPs) and ultrastructures of myelinated nerve fibers in injured spinal cords. Spinal cords of cats were injured expermentally at the second lumbar vertebra level with 20gm-20cm(400gm-cm) impact force using modified Allen's weight drop method. The animals were treated with TRH(2mg/Kg, bolus, then 2mg/Kg/hour, IV, for 4 hours) 1 hour after injury. SSEPs were checked serially in both treated and untreated groups for 24 hours. And the fine strucures of myelinated nerve fibers in the white matters were observed in electronmicroscope before and after the injury in both groups. In treated groups, the inital positive waves were re-elicited 3 hours after injury which was eliminated immediately after injury. Fine structure of the myelinated nerve fibers were changed progressively. With time after injury, the myelinated nerve fibers showed enlarged periaxonal spaces, irregulary contoured axons, and disarray of myelin sheaths. By 4 hours after injury, there appeared marked separation and disrray of myelin sheaths, and mitochondria and neurofibrils in axoplasm showed serve degeneration. The result of this study suggested that TRH has a beneficial effect on the re-elicitation of SSEP's and the preservation of myelinated nerve fibers in the acute stage of spinal cord injury.
Animals ; Axons ; Cats ; Evoked Potentials, Somatosensory* ; Mitochondria ; Myelin Sheath* ; Nerve Fibers, Myelinated* ; Neurofibrils ; Spinal Cord Injuries ; Spinal Cord* ; Spine ; Thyrotropin* ; Thyrotropin-Releasing Hormone*