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  • 1
    Electronic Resource
    Electronic Resource
    Developmental pattern of axonal pathways in the house shrew maxillary nerve (1996)
    Springer
    Anatomy and embryology 194 (1996), S. 205-213 
    Details
    ISSN: 1432-0568
    Keywords: Suncus murinus ; Somatotopy ; Vibrissae ; Fasciculation ; Sensory system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The topographic patterns of peripheral receptors and effectors seem to contribute to the construction of the neuronal circuit in the central nervous system (CNS) in mammals. Many patterns replicating those of the periphery have been found in the CNS, and fasciculation has been regarded as having a central role in the pattern replication. The house shrew, Suncus murinus, is an excellent species in which to study this topic because it has a vibrissae system arranged in a single ordered fashion and extraordinarily well-developed trigeminal spinal tracts. Using immunostaining and retrograde-tracing techniques, we examined the developmental pattern of the maxillary nervous system in the house shrew. The results indicate that the basic pattern of axonal extension reiterates with a parallel arrangement throughout the course of development except at a site in the brainstem where the central processes bifurcate into ascending and descending branches. Dorsoventral inversion of the peripheral pattern in the spinal tract occurs with this dualleveled bifurcation in association with the mediolaterally ordered entry of the central processes into the brainstem. The basic pattern of the central processes is established prior to the appearance of the vibrissae, indicating that the basic topographic pattern of the maxillary nerve is not related to the vibrissae system. The fasciculation pattern does not correspond to the overall layout of the arrays of vibrissae, and there are frequent exchanges of axons between fascicles both in the periphery and centrally. The parallel organization of the majority of the processes, together with the free exchange of processes between fascicles, suggests that these processes have an important role in the formation of the fasciculation and somatotopic patterns.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00187131
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  • 2
    Electronic Resource
    Electronic Resource
    Experimental odontogenic cysts induced by in vitro 4-nitroquinoline 1-oxide (4NQO) treatment of F344 rat incisor tooth germs (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of oral pathology & medicine 27 (1998), S. 0 
    Details
    ISSN: 1600-0714
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Miura Y, Ozaki HS, Li T-J, Uemura M, Kitano M: Experimental odontogenic cysts induced by in vitro 4-nitroquinoline 1-oxide (4NQO) treatment of F344 rat incisor tooth germs. J Oral Pathol Med 1998; 27: 53–8. © Munksgaard, 1998.This study was designed to establish an experimental animal model for elucidating the early stages of odontogenic cysts and tumors. It involves the in vitro treatment of tooth germs with 4-nitroquinoline 1-oxide (4NQO) at the early bell stage and their subsequent transplantation into the kidney subcapsular space. While all tooth germ transplants of the control group not exposed to the carcinogen showed continued tooth development with no pathological lesions, 21 of 23 4NQO-treated tooth germs developed into similar appearing keratinized cysts with or without associated tooth structures. The remaining two transplants failed to develop cysts and formed only a tooth. The present experimental procedure was effective in inducing keratinized cystic lesions that exhibit some similarities to human odontogenic keratocysts or primordial cysts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0714.1998.tb02093.x
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  • 3
    Electronic Resource
    Electronic Resource
    Prevention of Death of Axotomized Hypoglossal Neurones and Promotion of Regeneration by Chitin Grafting (2000)
    Springer
    Cellular and molecular neurobiology 20 (2000), S. 529-540 
    Details
    ISSN: 1573-6830
    Keywords: chitin ; biomaterials ; nerve regeneration ; hypoglossal nerve ; shrew
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. Chitin is known to promote skin wound healing. In this study, chitin, prepared from Zuwai crab shell, was used as a bridge between the proximal and distal stumps of cut hypoglossal nerves in shrews. We compared the effects of chitin on the regeneration of transected right hypoglossal nerve axons, with those of porcine dermis, bovine dermal aterocollagen, and autologous nerve bundles. 2. To assess the survival of neurones, the size of neuronal cell body, and number of motoneurones were determined in the absence of any bridged material and in the presence of porcine dermis, bovine dermal aterocollagen, chitin, or autologous nerve bundles as a bridge. 3. Our results revealed a significantly better outcome in chitin and autologous nerve bridged groups; the size of neuronal cell body and number of hypoglossal neurones were higher than in the other groups. Chitin also enhanced the regeneration of neurones; the number of horseradish peroxide positive neurones indicative of repaired axonal processes was significantly higher in chitin and autologous nerve-bridged groups than in other groups. 4. Our results demonstrated that the use of chitin sheet or autograft successfully prevented the death of severed neurones and promoted the regeneration of the lesioned nerve. Although the mechanisms underlying the effects of chitin are still unknown, chitin seems to be a potentially useful biocompatible material for nerve repair and regeneration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007055626632
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  • 4
    Electronic Resource
    Electronic Resource
    Collagen fibrils in the odontoblast layer of the rat incisor by scanning electron microscopy using the maceration method (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 239 (1994), S. 360-370 
    Details
    ISSN: 0003-276X
    Keywords: Rat incisor ; Dentin ; Pulp ; Collagen fibril ; von Korff fiber ; Scanning electron microscope ; Maceration method ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: There is not universal agreement on the existence of the extracellular pathway from the pulp along the odontoblast layer to the predentin.Method: To confirm this pathway, the architecture of collagen fibrils in the rat incisor dentin and pulp, especially in the odontoblast layer of the lateral (periodontal ligament) sides of the tooth, was demonstrated in the present investigation using scanning electron microscopy of the maceration method for collagen networks.Results: Numerous collagen bundles were observed in the odontoblast layer in the mature odontoblast region which, except for the young odontoblast region, comprises the major portion of the incisor. The collagen bundles went from the pulp, through the odontoblast layer, and were woven into the collagen network of the predentin. The meshwork structure was composed of fine secondary fibrils among these collagen bundles. The surface of the predentin contained many oval-shaped holes which were surrounded by collagen fibrils. Fracturing the dentin longitudinally relative to the dentinal tubules revealed that the arrangement of the collagen fibrils at the surface of the tubules was either circular or oblique. In the young odontoblast region, i.e., the thin portion from the apical end of the incisor where the mineralization of the dentin does not occur and where the height of the odontoblasts was less than 30 μm, many thick bundles composed of thick collagen fibrils ran straight from the pulp to the predentin through the odontoblast layer and fanned out into the collagen network of the predentin. These thick bundles might correspond to the so-called “von Korff fibers.” The distribution of collagen fibrils in the pulp was random except on the surface of the blood vessels where the fibrils comprised two sheets of collagen: the inner sheet which coursed longitudinally to the long axis of the vessel, and the outer sheet which ran transversely.Conclusion: It was considered that the fluid in the pulp could flow to the predentin along the collagen fibrils through the tight junction between the odontoblasts. © 1994 Wiley-Liss, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092390403
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