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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 70 (1986), S. 177-184 
    ISSN: 1432-0533
    Keywords: Rat sciatic nerve ; Peripheral nerve oedema ; Density measurements ; Wallerian degeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The formation of oedema in peripheral nerves was studied in rats at intervals varying from 6 h to 14 days after transection of the right sciatic nerve. Samples were removed proximal and distal to the injury, and the degree of oedema was determined by a microgravimetric method and by measurements of the water content and of the fascicular area. Distal to the lesion, decreased density values indicating the presence of oedema were observed in samples examined after a survival period of 6 h-14 days. The water content and fascicular area were both increased in samples taken 24 h after the injury. Fourteen days postinjury the water content had increased further. Proximal to the lesion, the water content and the fascicular area were increased in samples examined after a survival period of 24 h. Fourteen days after the injury, the increase in water content was even more pronounced. No changes were detected with the microgravimetric technique 6 and 24 h after the injury. Unexpectedly, animals surviving 14 days showed increased density values. The microgravimetric technique used is a valuable adjunctive method for quantitation of peripheral nerve oedema in the acute phase after a traumatic nerve injury. Later on, loss of axons and of myelin components, together with regenerative phenomena, influence the density values obtained. Quantitative methods for studying chronic peripheral nerve oedema should therefore, be supplemented with other techniques.
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  • 2
    ISSN: 1432-0533
    Keywords: DSP4 ; Noradrenaline ; Blood-brain barrier ; Brain edema ; Brain density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cerebral microvessels receive a noradrenergic innervation originating from the locus coeruleus. Previously, many studies have tried to elucidate the role of the central noradrenergic innervation on the blood-brain barrier (BBB). Many of them are based on chemical destruction of the innervation by local injection of 6-hydroxydopamine (6-OHDA) or physical injury to the locus coeruleus. Such methods are not selective and the results reported are contradictory. We have treated mice with a single i. p. injection of the compound,N-2-chloroethyl-N-ethyl-2-bromobenzylamine hydrochloride (DSP4). This substance induces a selective noradrenaline depletion and, unlike 6-OHDA, it can pass into the brain afer an i. p. injection. The animals were allowed to survive for 6 h to 60 days and the BBB was investigated with i.v.-injected horseradish peroxidase (HRP). Brain density values were also determined to find out if edema developed. The light microscopic distribution of HRP in the brain of DSP4-treated animals did not differ from that in control mice, i.e., there were no signs of increased BBB permeability to this protein tracer caused by DSP4. Density determinations revealed statistically significant reduced values in cerebrum (P〈0.005) and rhombencephalon (cerebellum) (P〈0.0005) of animals given 100 mg/kg body wt. of DSP4 indicating development of edema. A minor drop in density of the rhombencephalon (cerebellum) (P〈0.05 at 48 h) and of the cerebrum (statistically not significant) appeared when 50 mg/kg body wt. of DSP4 was injected. Our findings indicate that the BBB to proteins maintains its function but that edema, likely composed of an ultrafiltrate from the blood, will develop after an injection of DSP4. In view of its selective degenerative action on the noradrenergic central neurons, this kind of brain edema is probably a direct consequence of abnormal noradrenergic innervation of the cerebral blood vessels. Our observations are thus in line with the assumption that the noradrenergic innervation influences endothelial permeability in the central nervous system. Alternative pathogenetic mechanisms are discussed.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 81 (1990), S. 148-154 
    ISSN: 1432-0533
    Keywords: Spinal nerve roots ; Blood vessels ; Vascular permeability ; Lanthanum ; Evans blue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The permeability of blood vessels in rat spinal nerve roots was investigated with Evans blue-albumin as an in vivo macromolecular tracer and lanthanum as tracers as an electron microscopic ionic marker added to a fixative. Rats injected intravenously with Evans blue, showed macroscopic distinct staining of dorsal root ganglia, whereas spinal nerve roots remained unstained. Fluorescence microscopy, however, revealed clear extravascular fluorescence both in ventral and dorsal roots 2 or 18 h after tracer administration. Two different types of blood vessels exists in spinal nerve root; large extrinsic (radicular) in the root sheath and minute intrinsic vessels in the parenchyma. Lanthanum added to a fixative, perfused through the vessels was detected in the lumen of both types of vessels, usually adhering to the luminal plasma membrane and in many invaginations from that membrane. Lanthanum also entered the clefts between endothelial cells but was always stopped at the junctions which are, thus, of the tight type. Diffuse penetration of the compound into the cytoplasm was seen in one endothelial cell, but no fenestrations were detected. Junctions between the endothelial cells of vessel in rat spinal nerve roots are impermeable to lanthanum and most likely also to other large molecular substances like albumin. Thus, probable routes for serum albumin to enter the nerve rools, where it normally is present, must be either by centripetal extracellular diffusion from the ganglia and the peripheral nerve or by vascular leakage in the roots, caused by for instance pinocytosis across endothelial cells.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 85 (1993), S. 129-137 
    ISSN: 1432-0533
    Keywords: Spinal nerve roots ; Root sheath ; Structure ; Permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present study was carried out to investigate the permeability of normal spinal nerve root sheaths around dorsal and ventral roots in the rat. In vivo studies were performed using Evans bluealbumin and lanthanum chloride as tracers. The Evans blue-albumin complex is macromolecular in size and lanthanum ions are small and easily visible in the electron microscope. Both tracers were injected into the subarachnoid space and 15 min later samples were taken and further processed for detection of tracer. Postmortem studies with lanthanum was also performed. Following fixation by cardiac perfusion with fixative without tracer, lanthanum chloride was added to the fixative and applied directly to exposed spinal cord including the spinal nerve roots. Macroscopical examination showed Evans blue staining of the superficial blood vessels of the spinal cord, but no staining of the parenchyma of either spinal cord or nerve roots. Fluorescence microscopy revealed, in addition to a bright red fluorescence of root sheaths, a faint longitudinally orientated red fluorescence in the endoneurium of the nerve roots, indicating the presence of the dye-albumin complex. In both in vivo and post-mortem lanthanum studies, the tracer was detected between cell layers of the nerve root sheath and in invaginations of the plasma membrane of these cells, as well as inside the nerve root parenchyma. Some of the cells of the sheaths in post-mortem animals were diffusely marked with intracellular tracer. The endoradicular lanthanum was most often seen superficially, but lanthanum could occasionally be detected deeper in the parenchyma in the post mortem studies. The results show that the spinal nerve root sheaths are permeable to both the macromolecular substance Evans blue-albumin and the small lanthanum ion. No differences were detected between dorsal and ventral roots, nor between proximal and distal parts of the roots.
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  • 5
    ISSN: 1432-0533
    Keywords: Trauma ; Spinal cord injury ; Microvascular permeability ; Serotonin ; p-Chlorophenylalanine (p-CPA)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The possibility that serotonin can take part in the initiation of the increased microvascular permeability occurring in a spinal cord trauma was investigated in a rat model with 131I-sodium and lanthanum as tracers. We influenced the serotonin content in the tissue pharmacologically by treating animals with a serotonin synthesis inhibitor, p-chlorophenylalanine (p-CPA), before the production of the injury and compared the results with injured, untreated controls. A small incision was made in the dorsal horn of the lower thoracic cord. It caused a progressive extravasation of 131I-sodium in the damaged segment, measured after 1,2 and 5 h. Rostral and caudal segments also showed a significant but lower accumulation of 131I-sodium. Lanthanum added to the fixative was used as an ionic tracer detectable by electron microscopy. The endothelial cells of microvessels removed from the perifocal region after 5 h showed a marked increase in the number of lanthanum-filled vesicles. Many endothelial cells had a diffuse penetration of the tracer into the cytoplasm and the basement membrane. However, the tight junctions usually remained closed to lanthanum. Pretreatment with p-CPA markedly reduced the extravasation of 131I-sodium measured at 5 h in the traumatized cord. At the cellular level, the endothelial vesicles filled with lanthanum approached the condition of uninjured animals. The diffuse infiltration of lanthanum into endothelial cells and its spread into the basement membrane of the vascular wall were usually absent. Our results indicate that serotonin plays a role in the initiation of the increased microvascular permeability which occurs in spinal cord injuries.
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  • 6
    ISSN: 1432-0533
    Keywords: Spinal nerve roots ; Root sheath ; Cerebrospinal fluid ; Permeability ; Drainage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of the present investigation was to find out if a compound injected into the spinal subarachnoid space, after having entered ventral and dorsal nerve roots, can be traced to the epineurial-perineurial sheaths and the endoneurium of peripheral nerves. This would indicate a centrifugal movement of substances from the cerebrospinal fluid along nerves; one route of drainage of cerebrospinal fluid which in the past has been widely discussed. In vivo studies were made using Evans blue-albumin and lanthanum chloride as tracers. Evans blue-albumin is macromolecular in size and emits a red fluorescence after exposure to ultraviolet light. Lanthanum ions are small and easily visible in the electron microscope. The tracers were injected into the cervical subarachnoid space and 15 min to 24 h later sampled from roots, dorsal root ganglia, proximal part of spinal nerves and the median nerves were taken and further processed for detection of tracers. Fluorescence microscopy from samples removed 15 min and 24 h after the injection of Evans blue-albumin showed a red fluorescence of low intensity in the endoneurium of nerve roots, ganglia and proximal spinal nerve. After 24 h also the median nerve elicited some fluorescence. The sheaths around these structures were also fluorescent. Lanthanum was detected between cell layers of the nerve root sheath as well as inside the nerve root parenchyma. In about 50% of the samples from dorsal root ganglia extracellular lanthanum was found in the capsule. The tracer was also found in the epineurium of 50% of the spinal nerves and occasionally in the perineurium. At 15 min, 6 h and 15 h lanthanum was often present in the endoneurium of the spinal nerve sample but always absent in the median nerve. At 24 h electron-dense particles identical to, and suspected to be, lanthanum was rarely seen also in the median nerve. The results show that substances in the cerebrospinal fluid can be transferred to other parts of the peripheral nervous system indicating a centrifugal spread, which may take place in [1] extracellular spaces of the sheaths covering roots, ganglia and nerve, and [2] endoneurial spaces in roots, ganglia and nerve after passage across the sheath surrounding spinal nerve roots. If absorption of tracer into the blood occurs following injection into the subarachnoid space, leaky blood vessels in ganglia and epineurium may add tracer molecules to the extra-cellular environment of the peripheral nervous system.
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  • 7
    ISSN: 1434-4726
    Keywords: Formalin fixation ; Mucous cell ; Submandibular gland ; Morphology ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The features of mucous cells in 10% formalin (FA)-fixed submandibular glands differ markedly from those fixed in glutaraldehyde (GA). We therefore studied morphological changes in mucous cells during 10% FA fixation. Mucous cells were fixed in either 10% FA, neutral sodium-phosphate-buffered (Na-PBed) 10% FA, ice-cold 10% FA or an ice-cold fixative mixture of 2.0% paraformaldehyde (PA) and 0.5% GA. Two different methods were used: immersion fixation and venous perfusion fixation. The 10% FA-fixed tissues had elliptical or flattened nuclei, a clear cytoplasm and no secretory granules. Tissues fixed with the fixative mixture displayed almost round nuclei, a broad endoplasmic reticulum and abundant secretory granules in the cytoplasm. Tissues immersion-fixed with neutral Na-PBed 10% FA or perfusion-fixed with ice-cold 10% FA had almost the same light microscopic appearance as that of the mixture-fixed tissues. To elucidate the process of morphological changes during 10% FA fixation at room temperature, samples immersed in 10% FA for varying periods of time were postfixed immediately in the fixative mixture and exposed to microwave irradiation. This method produced a variety of findings, even within the same section. There was a significant difference in the findings seen in the center of the section and at the periphery. The initial changes caused by 10% FA were rupture of the secretory granules located in the perinuclear region and destruction of the perinuclear organelles such as Golgi apparatus, mitochondria and endoplasmic reticulum. Absorption of the endoplasmic reticulum progressed so that the pennuclear region became translucent. To obtain a better structure in mucous cells from the fixed submandibular gland tissues, an appropriate fixative such as GA should be used and the fixative should infiltrate into the tissue as quickly as possible.
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