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M Risling - One of the best experts on this subject based on the ideXlab platform.

  • ganglionic axons in motor roots and Pia Mater
    Progress in Neurobiology, 1997
    Co-Authors: Claes Hildebrand, M. Karlsson, M Risling
    Abstract:

    Abstract In addition to motor axons and preganglionic axons, ventral roots contain unmyelinated or thin myelinated sensory axons and postganglionic sympathetic axons. It has been said that ventral roots channel sensory axons to the CNS. However, it now seems that these axons end blindly, shift to the Pia or loop and return towards the periphery and that these units reach the CNS via dorsal roots. Sensory ventral root axons project from a variety of somatic or visceral receptors; some of them are third branches of dorsal root afferents and some seem to lack a CNS projection. Many ventral root afferents contain substance P (SP) and/or calcitonin gene-related peptide (CGRP). These fibres are not affected by neonatal capsaicin treatment and they cannot induce radicular or Pial extravasation. Some thin ventral root axons are sympathetic and relate to blood vessels. Afferents containing SP and/or CGRP and sympathetic axons also occur in the spinal Pia Mater. The sensory axons mediate pain. They might also have vasomotor, tissue-regulatory and/or mechanoreceptive functions. The motor roots of cranial nerves IV, VI and XI contain unmyelinated axons arranged like in ventral roots outside the autonomic outflow. However, the motor root of cranial nerve V channels some unmyelinated axons into the CNS. The occurrence of thin axons in ventral roots and Pia Mater changes during development and ageing. After peripheral nerve injury, ipsilateral ventral roots and Pia are invaded by new sensory and postganglionic sympathetic axons. © 1997 Elsevier Science Ltd. All Rights Reserved.

  • substance p calcitonin gene related peptide growth associated protein 43 and neurotrophin receptor like immunoreactivity associated with unmyelinated axons in feline ventral roots and Pia Mater
    The Journal of Comparative Neurology, 1994
    Co-Authors: M Risling, C J Dalsgaard, Jonas Frisen, A M Sjogren, Kaj Fried
    Abstract:

    The spinal Pia Mater receives a rich innervation of small sensory axons via the ventral roots. Other sensory axons enter the ventral roots but end blindly or turn abruptly in hairpin loop-like formations and continue in a distal direction. In the present study, the content of substance P (SP)-, calcitonin gene-related peptide (CGRP)-, growth-associated protein (GAP-43)-, and low-affinity neurotrophin receptor protein (p75NGFr)-like immunoreactivity (-LI) associated with these different types of sensory axons was assessed with light and electron microscopic immunohistochemical techniques. In addition, the binding of antibodies against synthetic peptides representing unique sequences of residues in the products of the trk and trkB protooncogenes was analyzed. These genes encode membrane spanning proteins, which have been shown to constitute specific high affinity binding sites for several members of the nerve growth factor family of neurotrophic factors. The results of the present study imply that the ventral root afferents comprise several different types of sensory axons, which all contain SP-, CGRP-, GAP-43-, and p75NGFr-like immunoreactivities. In addition, at least some of the presumed sensory fiber bundles in ventral roots and the Pia Mater were immunoreactive for the trkB gene product. Moreover, leptomenin-geal cells and nonneuronal cells of the ventral roots were shown to bind antibodies to both the trk and trkB gene products. The ventral root afferents seem to share their immunohistochemical pattern with pain-transducing axons at some other locations, such as the tooth pulp. The contents of SP- and CGRP-LI in sensory axons that reach the central nervous system (CNS) through the ventral root indicate that ventral root afferents may be involved in sensory mechanisms, such as the ventral root pain reaction, as well as in the control of the Pial blood vessels. The demonstration of GAP-43 and neurotrophin receptor-immunoreactivities associated with unmyelinated fibers in ventral roots and the Pia Mater is discussed in relation to previous reports on postnatal plasticity in these axonal populations. © 1994 Wiley-Liss, Inc.

  • aberrant regeneration of motor axons into the Pia Mater after ventral root neuroma formation
    Brain Research, 1992
    Co-Authors: M Risling, K Sorbye, Staffan Cullheim
    Abstract:

    Abstract The spinal Pia Mater receives a rich innervation of small sensory and autonomic axons via the ventral roots. In the present study this pathway was interrupted by the transection of the L7 ventral root in young kittens. The animals were killed 12–18 months postoperatively. It was observed that the Pia Mater adjacent to the divided ventral root contained large numbers of myelinated axons. We suggest that these axons represent sprouts which had reached the Pia Mater by retrograde growth from the neuroma on the ventral root. Some of these aberrant Pial axons ended blindly in the Pia Mater. Abnormal terminal-like swellings were observed along Pial blood vessels. Fibers with diameters exceeding 11 μm were observed. Many fibers had an internodal spacing below 100 μm and the maximum value was only about 300 μm. Thus, motor axons which are forced to grow into a foreign territory show a maldevelopment which is more obvious with regard to nodal spacing than to fiber diameter.

  • The Pia Mater - a conduit for regenerating axons after ventral root replantation.
    Restorative Neurology and Neuroscience, 1991
    Co-Authors: M Risling, Thomas Carlstedt, H. Lindå, Staffan Cullheim
    Abstract:

    Previous studies have shown that replantation of avulsed ventral roots may lead to functional reinnervation of hindleg muscles. Regenerating motor axons may regrow for a considerable distance within the spinal cord before entering the replanted ventral root. In this study we show, in the rat and monkey, that many regenerating axons utilize an alternative pathway along the surface of the spinal cord, i.e. the Pia Mater. This type of reinnervation takes place entirely in the peripheral nervous system.

Toyoko Nakagomi - One of the best experts on this subject based on the ideXlab platform.

  • Ischemia-Induced Neural Stem/Progenitor Cells in the Pia Mater Following Cortical Infarction
    Stem Cells and Development, 2011
    Co-Authors: Toyoko Nakagomi, Orie Saino, Martijn Clausen, Hiroo Yoshikawa, Nami Nakagomi, Akihiko Taguchi, Shuji Kubo, Zoltán Molnár, Akiko Nakano-doi, Tomohiro Matsuyama
    Abstract:

    Increasing evidence shows that neural stem/progenitor cells (NSPCs) can be activated in the nonconventional neurogenic zones such as the cortex following ischemic stroke. However, the precise origin, identity, and subtypes of the ischemia-induced NSPCs (iNSPCs), which can contribute to cortical neurogenesis, is currently still unclear. In our present study, using an adult mouse cortical infarction model, we found that the leptomeninges (Pia Mater), which is widely distributed within and closely associated with blood vessels as microvascular pericytes/perivascular cells throughout central nervous system (CNS), have NSPC activity in response to ischemia and can generate neurons. These observations indicate that microvascular pericytes residing near blood vessels that are distributed from the leptomeninges to the cortex are potential sources of iNSPCs for neurogenesis following cortical infarction. In addition, our results propose a novel concept that the leptomeninges, which cover the entire brain, have an ...

  • ischemia induced neural stem progenitor cells in the Pia Mater following cortical infarction
    Stem Cells and Development, 2011
    Co-Authors: Orie Saino, Martijn Clausen, Hiroo Yoshikawa, Akihiko Taguchi, Shuji Kubo, Toyoko Nakagomi, Zoltán Molnár, Akiko Nakanodoi, Nami Nakagomi
    Abstract:

    Increasing evidence shows that neural stem/progenitor cells (NSPCs) can be activated in the nonconventional neurogenic zones such as the cortex following ischemic stroke. However, the precise origin, identity, and subtypes of the ischemia-induced NSPCs (iNSPCs), which can contribute to cortical neurogenesis, is currently still unclear. In our present study, using an adult mouse cortical infarction model, we found that the leptomeninges (Pia Mater), which is widely distributed within and closely associated with blood vessels as microvascular pericytes/perivascular cells throughout central nervous system (CNS), have NSPC activity in response to ischemia and can generate neurons. These observations indicate that microvascular pericytes residing near blood vessels that are distributed from the leptomeninges to the cortex are potential sources of iNSPCs for neurogenesis following cortical infarction. In addition, our results propose a novel concept that the leptomeninges, which cover the entire brain, have an ...

  • Ischemia-Induced Neural Stem/Progenitor Cells in the Pia Mater Following Cortical Infarction
    Stem Cells and Development, 2011
    Co-Authors: Toyoko Nakagomi, Akiko Nakano-doi, Orie Saino, Martijn Clausen, Hiroo Yoshikawa, Nami Nakagomi, Akihiko Taguchi, Shuji Kubo, Zoltán Molnár, Tomohiro Matsuyama
    Abstract:

    Increasing evidence shows that neural stem/progenitor cells (NSPCs) can be activated in the nonconventional neurogenic zones such as the cortex following ischemic stroke. However, the precise origin, identity, and subtypes of the ischemia-induced NSPCs (iNSPCs), which can contribute to cortical neurogenesis, is currently still unclear. In our present study, using an adult mouse cortical infarction model, we found that the leptomeninges (Pia Mater), which is widely distributed within and closely associated with blood vessels as microvascular pericytes/perivascular cells throughout central nervous system (CNS), have NSPC activity in response to ischemia and can generate neurons. These observations indicate that microvascular pericytes residing near blood vessels that are distributed from the leptomeninges to the cortex are potential sources of iNSPCs for neurogenesis following cortical infarction. In addition, our results propose a novel concept that the leptomeninges, which cover the entire brain, have an important role in CNS restoration following brain injury such as stroke.

Miguel Angel Reina - One of the best experts on this subject based on the ideXlab platform.

  • ultrastructural findings in human spinal Pia Mater in relation to subarachnoid anesthesia
    Anesthesia & Analgesia, 2004
    Co-Authors: Miguel Angel Reina, Oscar De León Casasola, M C Villanueva, Fabiola Machés, Andrés López, Jose De Andres
    Abstract:

    We examined ultrastructural details such as the cellular component and membrane thickness of human spinal Pia Mater with the aim of determining whether fenestrations are present. We hypothesized that Pia Mater is not a continuous membrane but, instead, that there are fenestrations across the Pial cellular membrane. The lumbar dural sac from 7 fresh human cadavers was removed, and samples from lumbar spinal Pia Mater were studied by special staining techniques, immunohistochemistry, and transmission and scanning electron microscopy. A Pial layer made by flat overlapping cells and subPial tissue was identified. We found fenestrations in samples from human spinal Pia Mater at the thoracic-lumbar junction, conus medullaris, and nerve root levels, but these fenestrations did not appear at the thoracic level. We speculate whether the presence of fenestrations in human spinal Pia Mater at the level of the lumbar spinal cord and at the nerve root levels has any influence on the transfer of local anesthetics across this membrane.

  • Ultrastructural Findings in Human Spinal Pia Mater in Relation to Subarachnoid Anesthesia
    Anesthesia and Analgesia, 2004
    Co-Authors: Miguel Angel Reina, Oscar De León Casasola, M C Villanueva, Fabiola Machés, Andrés López, José Antonio De Andrés
    Abstract:

    UNLABELLED: We examined ultrastructural details such as the cellular component and membrane thickness of human spinal Pia Mater with the aim of determining whether fenestrations are present. We hypothesized that Pia Mater is not a continuous membrane but, instead, that there are fenestrations across the Pial cellular membrane. The lumbar dural sac from 7 fresh human cadavers was removed, and samples from lumbar spinal Pia Mater were studied by special staining techniques, immunohistochemistry, and transmission and scanning electron microscopy. A Pial layer made by flat overlapping cells and subPial tissue was identified. We found fenestrations in samples from human spinal Pia Mater at the thoracic-lumbar junction, conus medullaris, and nerve root levels, but these fenestrations did not appear at the thoracic level. We speculate whether the presence of fenestrations in human spinal Pia Mater at the level of the lumbar spinal cord and at the nerve root levels has any influence on the transfer of local anesthetics across this membrane. IMPLICATIONS: The ultrastructural anatomy of the human Pia Mater, such as Pial cells, membrane thickness, and subPial tissue at different levels of the thoracic and lumbar spinal cord and nerve roots, was studied by special staining techniques, immunohistochemistry, and transmission and scanning electron microscopy. Fenestrations were found in samples at the thoracic-lumbar junction, conus medullaris, and nerve root levels. No fenestrations were found in samples at the thoracic level. At present, we cannot determine the significance of these findings.

Reinhard Grebe - One of the best experts on this subject based on the ideXlab platform.

  • Tensile strength of cranial Pia Mater: preliminary results
    Journal of Neurosurgery, 2004
    Co-Authors: Patrick Aimedieu, Reinhard Grebe
    Abstract:

    OBJECT: The goal of this study was to determine the tensile strength of cranial Pia Mater. METHODS: Samples of isolated bovine cranial Pia Mater were subjected to quasistatic traction to evaluate its tensile strength. The experimental curves of physiological deformation that were obtained can be subdivided into three parts that represent different mechanical properties: the nonlinear initial part of the curve demonstrates increasing stiffness, followed by a quasilinear pattern of elastic behavior, and finally a negative relationship (slope) between force and elongation, which characterizes a progressive deterioration. These three steps precede final sample rupture. The stiffness of the Pia Mater was calculated for both the initial and the linear (elastic) parts of the mean curve. The initial part and the elastic part of the curve show a typical stiffness value of 0.024 N/mm and 0.19 N/mm, respectively. The maximal mean force and corresponding maximal deformation that were attained were 1.1 N and 0.19, respectively. CONCLUSIONS: Although very thin and apparently fragile, Pia Mater exhibits an unexpectedly high level of stiffness and should have a significant influence on total brain mechanical properties in response to loading.

  • tensile strength of cranial Pia Mater preliminary results
    Journal of Neurosurgery, 2004
    Co-Authors: Patrick Aimedieu, Reinhard Grebe
    Abstract:

    Object. The goal of this study was to determine the tensile strength of cranial Pia Mater. Methods. Samples of isolated bovine cranial Pia Mater were subjected to quasistatic traction to evaluate its tensile strength. The experimental curves of physiological deformation that were obtained can be subdivided into three parts that represent different mechanical properties: the nonlinear initial part of the curve demonstrates increasing stiffness, followed by a quasilinear pattern of elastic behavior, and finally a negative relationship (slope) between force and elongation, which characterizes a progressive deterioration. These three steps precede final sample rupture. The stiffness of the Pia Mater was calculated for both the initial and the linear (elastic) parts of the mean curve. The initial part and the elastic part of the curve show a typical stiffness value of 0.024 N/mm and 0.19 N/mm, respectively. The maximal mean force and corresponding maximal deformation that were attained were 1.1 N and 0.19, res...

Tony M. Keaveny - One of the best experts on this subject based on the ideXlab platform.

  • Effects of white, grey, and Pia Mater properties on tissue level stresses and strains in the compressed spinal cord.
    Journal of Neurotrauma, 2009
    Co-Authors: Carolyn J. Sparrey, Geoffrey T. Manley, Tony M. Keaveny
    Abstract:

    Recent demographics demonstrate an increase in the number of elderly spinal cord injury patients, motivating the desire for a better understanding of age effects on injury susceptibility. Knowing that age and disease affect neurological tissue, there is a need to better understand the sensitivity of spinal cord injury mechanics to variations in tissue behavior. To address this issue, a plane-strain, geometrically nonlinear, finite element model of a section of a generic human thoracic spinal cord was constructed to model the response to dorsal compression. The Material models and stiffness responses for the grey and white matter and Pia Mater were varied across a range of reported values to observe the sensitivity of model outcomes to the assigned properties. Outcome measures were evaluated for percent change in magnitude and alterations in spatial distribution. In general, principal stresses (114–244% change) and pressure (75–119% change) were the outcomes most sensitive to Material variation. Strain outcome measures were less sensitive (7–27% change) than stresses (74–244% change) to variations in Material tangent modulus. The Pia Mater characteristics had limited (

  • effects of white grey and Pia Mater properties on tissue level stresses and strains in the compressed spinal cord
    Journal of Neurotrauma, 2009
    Co-Authors: Carolyn J. Sparrey, Geoffrey T. Manley, Tony M. Keaveny
    Abstract:

    Recent demographics demonstrate an increase in the number of elderly spinal cord injury patients, motivating the desire for a better understanding of age effects on injury susceptibility. Knowing that age and disease affect neurological tissue, there is a need to better understand the sensitivity of spinal cord injury mechanics to variations in tissue behavior. To address this issue, a plane-strain, geometrically nonlinear, finite element model of a section of a generic human thoracic spinal cord was constructed to model the response to dorsal compression. The Material models and stiffness responses for the grey and white matter and Pia Mater were varied across a range of reported values to observe the sensitivity of model outcomes to the assigned properties. Outcome measures were evaluated for percent change in magnitude and alterations in spatial distribution. In general, principal stresses (114–244% change) and pressure (75–119% change) were the outcomes most sensitive to Material variation. Strain outcome measures were less sensitive (7–27% change) than stresses (74–244% change) to variations in Material tangent modulus. The Pia Mater characteristics had limited (<4% change) effects on outcomes. Using linear elastic models to represent non-linear behavior had variable effects on outcome measures, and resulted in highly concentrated areas of elevated stresses and strains. Pressure measurements in both the grey and white matter were particularly sensitive to white matter properties, suggesting that degenerative changes in white matter may influence perfusion in a compressed spinal cord. Our results suggest that the mechanics of spinal cord compression are likely to be affected by changes in tissue resulting from aging and disease, indicating a need to study the biomechanical aspects of spinal cord injury in these specific populations.