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  • 1
    Electronic Resource
    Electronic Resource
    Patterns of neuroglial proliferation in spinal cord white matter following exposure to ionizing radiation (1979)
    Springer
    Cellular and molecular life sciences 35 (1979), S. 1237-1237 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary X-irradiation temporarily decreases the proliferative activity of neuroglia in immature rat spinal cord. Later, the proliferative activity in these irradiated regions surpasses that noted in control rats. Areas adjacent to the irradiated region have a greater than normal percentage of labelled neuroglia and may also be a source for neuroglia which re-populate the irradiated zone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01963311
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  • 2
    Electronic Resource
    Electronic Resource
    Membrane ultrastructure of developing axons in glial cell deficient rat spinal cord (1985)
    Springer
    Journal of neurocytology 14 (1985), S. 79-104 
    Details
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In order to investigate axolemmal development in a glial cell deficient environment, normal and irradiated dorsal funiculus in rat lumbosacral spinal cord was examined by freeze-fracture electron microscopy. At 3 days of age, normal fibres are all unmyelinated and of small (〈0.5 μm) diameter. The unmyelinated axons have a moderate density (∼850 μm−2) of intramembranous particles (IMPs) on P-fracture faces and a low IMP density (∼300 μm−2) on E-faces. IMPs are homogeneously distributed along both fracture faces. By 19 days of age, the normal dorsal funiculus is well populated with myelinated axons and glial cells, as well as a sizable population of unmyelinated fibres. Nearly all of the myelinated fibres have a large (〉1.0 μm) diameter; whereas, most unmyelinated axons are of small (〈0.5 μm) calibre. The axolemma of unmyelinated axons is relatively undifferentiated, with an asymmetrical distribution of IMPs (P-face: ∼1100 μm−2; E-face: ∼450 μm−2). Myelinated fibres show nodal and paranodal regions with P-face and E-face ultrastructure similar to previous descriptions. Internodal axolemma appears relatively homogeneous, with P-faces being highly particulate (∼2100 μm−2) and a low IMP density (∼200 μm−2) on E-faces. Following irradiation of the lumbosacral spinal cord at 3 days of age, there is a severe reduction in the number of glial cells and myelinated fibres in this region when the tissue is examined at 19 days of age. Despite the deficiency of glial cells in this tissue, axonal and axolemmal development continue. Numerous large (〉1.0 μm) diameter axons are present in this irradiated tissue. Large diameter axons show a high (∼2000 μm−2) density of IMPs on P-faces; E-face IMP density remains at ∼440 μm−2. Small calibre axons also have an asymmetrical distribution of particles (P-face: ∼1100 μm−2; E-face: 280 μm−2). The axolemmal E-faces of some glial cell deprived fibres exhibit regions with greater than normal (∼750 μm−2) density of IMPs. These results demonstrate that some aspects of axonal and axolemmal development continue in a glial cell deficient environment, and it is suggested that axolemmal ultrastructure is, at least in part, independent of glial cell association.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01150264
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  • 3
    Electronic Resource
    Electronic Resource
    On the presence of peripheral-like nervous and connective tissue within irradiated spinal cord (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 160 (1968), S. 675-689 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Cells with elongated nuclei resembling those of fibroblasts and/or Schwann cells had been noted previously in x-irradiated portions of rat spinal cords. The present experiment was undertaken to determine the identity and fates of these cells. For this experiment, a 5 mm length of lumbosacral spinal cord was irradiated (4000 R) in three-day-old Holtzman rats. Groups of these rats and their litter mate controls were killed at intervals from 11 through 60 days following irradiation. Most of the spinal cords were prepared for light microscopic examination; a few were prepared for ultrastructural studies. Light microscopic examination revealed that the cells in question became observable near the dorsal roots within and immediately caudal to the irradiated area in a few rats as early as 15 days post-irradiation and in all rats by 19 days following irradiation. The number of cells increased rapidly and in some cases filled the dorsal funiculi. Axons that were intermingled with these cells usually became myelinated approximately 25 days post-irradiation. The myelin that formed on these axons resembled peripheral rather than central myelin. Reticular fibers were also abundant in the cell aggregations. The ultrastructural studies confirmed these observations. The data indicate that these cells were involved in formation of peripheral-like nervous tissue within the spinal cord of all irradiated rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091600403
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  • 4
    Electronic Resource
    Electronic Resource
    Neuroglial population in the spinal white matter of neonatal and early postnatal rats: An autoradiographic study of numbers of neuroglia and changes in their proliferative activity (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 171 (1971), S. 283-291 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The temporal pattern of increase in number of neuroglia in spinal cord white matter and the amount of multiplication in situ of these cells were studied in rats ranging from less than 12 hours following birth to 30 days of age. Autoradiographs of sections from animals killed four hours after injection of tritiated thymidine were studied; counts of the total neuroglial population and of the number of labeled neuroglia were made in the white matter of each half of the cord (hemisection). During the first two weeks following birth, the number of neuroglia per hemisection increased six times; thereafter, the population appeared to be stable. The increases in number of labeled neuroglia appeared to parallel the rise in total population, particularly during the period of greatest population increase, i.e., days 7 through 12. After 12 days, when the total population stabilized, there was a marked and rapid decrease in the number of labeled cells. The walls of the central canal were examined in view of the role this area plays in the initial development of the nervous system. In rats killed during the first 14 days postnatally, the dorsal and ventral walls were incomplete; however, numerous, unidentified cells adjacent to these walls were oriented as if entering the dorsal median septum and the ventral median sulcus. By 22 days the central canal area had more of its adult appearance.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091710208
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  • 5
    Electronic Resource
    Electronic Resource
    Autoradiographic studies of intramedullary schwann cells in irradiated spinal cords of immature rats (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 171 (1971), S. 517-527 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This investigation examined the development of intramedullary Schwann cells. The presence of these cells in spinal cords of rats irradiated when three days old and examined 15 or more days later had been noted previously in this laboratory. The present study is an autoradiographic evaluation of spinal cords from groups of rats receiving a single injection of tritiated thymidine at an interval from 7 to 15 days after irradiation (3 days of age) and killed four hours to seven days following injection. The earliest post-irradiation interval at which the intramedullary Schwann cells were present was at nine days in only one animal. These cells were seen in approximately half of the rats injected and killed 11 days after irradiation and in all in the 15-day-group. In all of these cases the animals were killed four hours after injection of tritiated thymidine and a portion of this cell population was labeled. When the time between injection and autopsy was delayed for three or seven days, a decrease in intensity of the labeling was apparent and many cells were lightly labeled, indicating that cell proliferation had occurred. Although the evidence was not conclusive, the results suggested that the intramedullary Schwann cells were probably progeny of cells derived from the dorsal roots, the latter cells having been stimulated to migrate into and to divide within the spinal cord.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091710408
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  • 6
    Electronic Resource
    Electronic Resource
    Alterations in blood vessels in X-irradiated spinal cords of young rats (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 163 (1969), S. 89-99 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Administration of x-rays (4000 r) to lumbar spinal cords of three-day-old rats caused a loss of neuroglia with an inhibition of myelinogenesis, neuronal damage and necrosis. In contrast, the loss of neuroglia following administration of 2000 r is temporary, with myelinogenesis occurring later than normal. Preliminary observations suggested that differences in vascular responses to these two amounts of x-rays might account for these differing fates of the spinal cords; therefore, this investigation was designed to study further the reactions of the intramedullary vessels.Rats, irradiated when three days of age, were killed 1 to 27 days later. Some were killed by perfusion with Monolite Fast Blue BNVSA Paste, a substance retained in the vessels and readily visualized on microscopic examination. The remaining rats were decapitated, and spinal cords were stained by Gomori's method for alkaline phosphatase. The earliest consistent alteration, a decreased number of vessels, was noted seven days following irradiation with either dose. Rats receiving 4000 r had marked losses of blood vessels, vasodilatation and necrosis by 15 days post-irradiation; whereas, a decreased number of vessels was the only change noted in rats irradiated with 2000 r. Alterations in rats receiving 4000 r remained the same or became more severe throughout the study; spinal cords in rats receiving 2000 r returned to normal. These vascular alterations correlate well with the changes in other spinal cord components described previously by this investigator.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091630111
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  • 7
    Electronic Resource
    Electronic Resource
    Intramedullary schwann cell development following x-irradiation of mid-thoracic and lumbosacral spinal cord levels in immature rats (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 197 (1980), S. 85-93 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Intramedullary Schwann cells have been observed following x-irradiation of lumbosacral spinal cords in immature rats. The present investigation was designed to determine whether or not the development of intramedullary Schwann cells within the spinal cord could be influenced by the portion of the spinal cord exposed to radiation. Three groups of rats were irradiated when three days of age. In one group the irradiated zone was limited to a 5 mm length of mid-thoracic spinal cord (T only), in another group the irradiation was limited to a 5 mm length of lumbosacral spinal cord (L only), and in a third group 5 mm lengths of both mid-thoracic and lumbosacral spinal cord (T/L) were irradiated. All of these animals received a single exposure to 4000 R of soft x-rays (HVL 0.16 mm Al). Sham-irradiated littermates served as control animals. Groups of rats were killed at intervals from 9 through 60 days following irradiation, and the spinal cords were prepared for light microscopic examination. Schwann cells appeared in the lateral portion of the lumbosacral dorsal funiculi of L only and T/L irradiated spinal cords as early as 9 days post-irradiation. By 19 days post-irradiation Schwann cells occupied the lateral, medial, and deep medial portions of the dorsal funiculi in the lumbosacral areas. By 25 days post-irradiation Schwann cells were also observed in the dorsal gray horns. In contrast, Schwann cells were not observed in the midthoracic regions of T only and T/L irradiated rats until 11 days post-irradiation. The accumulation of these cells was not extensive, and, in general, the Schwann cells were confined to the lateral portion of the dorsal funiculi in all animals. These findings indicate that intramedullary Schwann cell development is influenced by the region of spinal cord irradiated in immature rats.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091970108
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  • 8
    Electronic Resource
    Electronic Resource
    Proliferation of non-neuronal cells in spinal cords of irradiated, immature rats following transection of the sciatic nerve (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 181 (1975), S. 799-811 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Transection of a peripheral nerve not only elicits changes in the injured neurons but also results in an increase in non-neuronal cells, considered by most workers to be neuroglia, in the region of these neurons. Since studies in this laboratory have shown that the neuroglial population of spinal cords of immature rats can be reduced markedly by ionizing radiation, the present investigation was undertaken to determine if this reaction would occur in the irradiated spinal cord following transection of the sciatic nerve. In order to answer this question the sciatic nerve was sectioned unilaterally at 17 days of age (14 days post-irradiation). Sham-irradiated littermates served as controls. Light microscopic examination showed an increase in non-neuronal cells throughout the gray matter on the side of axotomy in spite of a decreased neuroglial population in the 2,000 R and 3,000 R groups. These cells were scattered in the neuropil or were adjacent to injured neuronal perikarya in the anterior horn. Qualitatively similar reactions occurred in the 500 R and 1,000 R groups and in shamirradiated controls. Whether the magnitude of response is the same in all groups is currently under investigation, as are questions dealing with the origins of the reactive cells.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091810411
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  • 9
    Electronic Resource
    Electronic Resource
    Intraspinal non-neuronal cellular responses to peripheral nerve injury (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979), S. 369-387 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The accumulation of non-vascular, non-neuronal cells (designated herein as reactive cells) in association with perikarya of axotomized motor neurons has been described by many investigators. Recently Gilmore ('75) found that sciatic axotomy in immature rats resulted in the occurrence of reactive cells not only in the spinal ventral gray matter but also in the dorsal gray matter. To determine if the presence of these cells in the dorsal gray matter, a finding not reported by others, was related to the immaturity of the animal, sciatic axotomy was performed in rats ranging in age from 17 days to 16 months in the present study. Light microscopic evaluation of the spinal cords three or seven days post-operatively showed that the reactive cells occurred consistently in both dorsal and ventral gray matter irrespective of age. Transection of tibial nerve or the nerve to the medial head of the gastrocnemius muscle elicited a cellular response in both dorsal and ventral gray matter, although transection of the latter nerve resulted in a much less obvious response. Crushing of the sciatic nerve was followed by a response of reactive cells not qualitatively different from that noted following transection. Transection of the sural nerve, primarily a sensory nerve, resulted in the presence of reactive cells in dorsal gray matter but not in the environs of motor neurons in the ventral gray matter. These findings suggest that the reactive cells in the dorsal gray matter of the spinal cord are associated with altered central processes of dorsal root ganglion cells.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091940305
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  • 10
    Electronic Resource
    Electronic Resource
    Spinal nerve root degeneration in aging laboratory rats: A light microscopic study (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 174 (1972), S. 251-257 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Degeneration of unknown etiology was noted in the spinal nerve roots of aging rats. These animals (Charles River CD® rats) were included in a study of long-term effects of ionizing radiation. The initial lesion was a de-myelination of an individual axon or a few, isolated, scattered axons in the ventral roots of rats between 18 and 20 months of age. As the lesion progressed, the dorsal roots showed involvement, and by 24 months the usual finding was marked degeneration in ventral roots with degenerative changes of a lesser degree in the dorsal roots. When degeneration was complete, connective tissue filled the regions normally occupied by neural tissue. The lesion was unrelated to the radiation procedure, occurring with equal frequency in both irradiated and non-irradiated animals. Furthermore, lesions occurred with equal frequency in both males and females. The one factor to which the lesion appeared to be related was age since it was not observed in animals less than 18 months old but was seen in 66.7% of those between 18 and 20 months and in 96.0% of those older than 20 months. These data indicate that this lesion needs to be considered when using aging laboratory rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091740209
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