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  • 1
    Electronic Resource
    Electronic Resource
    Distribution of capillaries in relation to the life cycle of odontoblasts in the rat incisor (1986)
    Springer
    Anatomy and embryology 175 (1986), S. 189-198 
    Details
    ISSN: 1432-0568
    Keywords: Capillaries ; Tooth pulp ; Odontoblasts ; Mineralisation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Although the rat incisor is used widely in the study of dentinogenesis there is little information on the pulp capillaries and the fate of the pulp contents incisally. The capillaries have now been described in relation to the life cycle of the odontoblasts using light microscopy on perfusion fixed teeth and SEM on pulp vascular casts. Odontoblast precursors differentiated to preodontoblasts in the absence of local vessels. Capillaries entered the zone subjacent to preodontoblasts prior to their transformation to odontoblasts. They invaded the odontoblast layer after formation of odontoblast processes and during lengthening of their cell bodies. These capillaries formed a dense plexus which was separated from the predentine by about 10 μm thickness of odontoblast cytoplasm. Electron microscopy near the incisal end showed that the odontoblasts lost their processes and their polarity to form postodontoblasts. This coincided with the deposition of atubular collagenous tissue at the periphery of the pulp. Loss of fenestrations in the capillaries seemed to coincide with the diminution of odoncoblast function. Odontoblastic capillaries were lost before the postodontoblasts became separated from one another. There was evidence of degenerating vessels, cells and extracellular debris near the incisal end. Light and transmission electron microscopical evidence from demineralised teeth was correlated with SEM evidence from anorganically prepared specimens and considered in relation to dynamic events at the incisal surface. Thus the pulp closure region was found to include a central zone of mineralised, moribund pulp cells and debris surrounded by atubular tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00389595
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  • 2
    Electronic Resource
    Electronic Resource
    An investigation of pulp capillaries and tight junctions between odontoblasts in cats (1987)
    Springer
    Anatomy and embryology 177 (1987), S. 131-138 
    Details
    ISSN: 1432-0568
    Keywords: Capillaries ; Tooth pulp ; Tight junctions ; Odontoblasts ; Ultrastructure ; Mineralisation ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relative roles of capillaries and odontoblasts in the process of dentinogenesis and in pulp reactions to trauma and pathology are not clear. Contributing to the problem is the paucity of information on odontoblast —capillary relationships and tight junctions between odontoblasts. Using light microscopy the capillaries have now been examined in semithin transverse sections of perfusion fixed teeth at different positions in the long axis from the apical foramina to the pulp horns. Odontoblastic capillaries were prominent in the coronal and middle regions of canines and present at the same levels of incisors. In the pulp horns and just coronal to the pulp horns capillaries were all subodontoblastic but near the apex there were also a few odontoblastic capillary profiles. Transmission electron microscopy on ultrathin sections revealed that a high proportion of middle and coronal odontoblastic capillary profiles were fenestrated but subodontoblastic profiles coronal to the pulp horns were the most fenestrated. In a search for tight junctions in ultrathin sections some typical strands were observed between odontoblasts. The difficult of obtaining the latter evidence was explained by the cellular arrangement of the odontoblasts which differed markedly from an ideal parallel, apically coplanar arrangement. The results question the possibility that there is a direct exchange of materials between pulp capillaries and dentine in teeth of limited growth and provide a baseline for future experiments to test the permeability of the odontoblast layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00572537
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  • 3
    Electronic Resource
    Electronic Resource
    Electron microscopic studies on the potential loss of crystallites from routinely processed sections of young enamel in the rat incisor (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 202 (1982), S. 177-186 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Newly formed rat incisor enamel was fixed aqueously by perfusion with glutaraldehyde and anhydrously by immersion in ethylene glycol. Ultrathin sections were studied using transmission electron microscopy and electron diffraction. Aqueously processed enamel was shown to lose its mineral content when sectioned on distilled water. This mineral loss was minimized by limiting the exposure of sections to the water. In such preparations, enamel crystallites were seen by virtue of their intrinsic electron density only. Selected area electron diffraction provided corroborative evidence for the presence or absence of crystallites in the sections. Observations on mineralized sections and on stained mineralized and distilled-water-demineralized sections revealed organic material apparently in the same location as the crystallites. Anhydrously processed enamel which was sectioned on ethylene glycol showed a similar appearance of the crystallites. This appearance was not obviously altered after staining despite evidence that organelles in the ameloblasts were stained. In view of the observations that both methods yielded similar crystallite morphology, it was concluded that aqueous techniques can be used to study the relationship between organic and inorganic components. However, valid description of crystallites in such preparations requires minimal exposure of ultrathin sections to water.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092020202
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  • 4
    Electronic Resource
    Electronic Resource
    Evidence for tight junctions between odontoblasts in the rat incisor (1985)
    Springer
    Cell & tissue research 239 (1985), S. 137-140 
    Details
    ISSN: 1432-0878
    Keywords: Lanthanum ; Odontoblasts ; Tight junctions ; Tooth pulp ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Odontoblasts are known to be involved in the process of dentinogenesis but it is not clear whether substances may also be deposited in predentine and dentine by passing between these cells. Although tight junctions have been described, it is not clear if they are macular or “leaky” as opposed to continuous or “tight”. In this study use has been made of the permeability of fenestrated capillaries amongst the odontoblasts to deposit the penetrative tracer lanthanum in the interodontoblastic space. This was done by perfusion of anaesthetized rats with physiological solutions containing lanthanum nitrate at 37° C. Immersion fixation of transverse segments of mandibular incisors and examination with an electron microscope showed that lanthanum could permeate 40–50 μm between the odontoblasts to reach the peripheral pulp. Towards the predentine, often less than 10 μm from the capillaries, its progress was abruptly and completely halted by the junctions at the apical ends of the odontoblast cell bodies. Lanthanum was not found in the predentine. The mature secretory odontoblasts in the rat incisor have therefore been shown to be joined by continuous tight junctions. In the process of dentinogenesis this means that all substances deposited in predentine and dentine must arrive by passing through the odontoblasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214913
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  • 5
    Electronic Resource
    Electronic Resource
    Vascular permeability to lanthanum in the rat incisor pulp (1985)
    Springer
    Cell & tissue research 239 (1985), S. 131-136 
    Details
    ISSN: 1432-0878
    Keywords: Capillary permeability ; Lanthanum ; Peripheral nerves ; Tooth pulp ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Experiments were performed to compare the permeability of capillaries supplying the endoneurial environment, which is invested by perineurium, with vascular permeability in the pulp where perineurium is absent. Anaesthetised rats were perfused through the aorta with physiological solutions containing lanthanum nitrate at 37° C. Pieces of inferior alveolar nerve and segments of mandibular incisors were immersion-fixed and transverse sections were examined electron microscopically for the distribution of lanthanum. In the pulp the nerve fibres pass between lanthanum-impermeable arterioles and venules en route to the incisal end. In the peripheral pulp a few capillaries were permeable but the most permeable capillaries lay between the odontoblasts. Pulpal capillary permeability was attributed to the fenestrated endothelium and contrasted with the unfenestrated endoneurial capillaries which were impermeable to lanthanum. Whereas the tight junctions of endoneurial capillaries are known to prevent certain blood-borne substances from entering the endoneurium, it was not clear whether the permeability of the pulpal capillaries, which are distant from the nerve fibres, could affect the nerve fibre environment. No extravasated lanthanum reached the pulpal nerve fibres suggesting that they are not affected. Technically it was not possible to examine the incisal third of the tooth where the situation could be different because the volume of the pulp decreases and capillaries lie closer to the nerve fibres.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214912
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  • 6
    Electronic Resource
    Electronic Resource
    A fine-structural survey of the pulpal innervation in the rat mandibular incisor (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 160 (1981), S. 213-229 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The innervation of the rat incisor pulp has been studied using transmission electron microscopy and light microscopy. Transverse sections of mandibular incisor pulp (380-460 gm rats) from numerous positions in the long axis of the tooth were examined systematically in the electron microscope. Quantitative data on total axon populations were obtained. The nerve fibers were found to pass through the lingual half of the pulp from the apical end to within 2 mm of the incisal tip. Although the nerve fibers were seen to lie amongst the connective tissue cells between the blood vessels, the electron microscopic observations showed that the blood vessels are not innervated. Throughout their pulpal course the nerve fibers showed no trace of perineurial investment. Virtually all the axons were unmyelinated. Total numbers of axons were small (233-328) and peak diameters of 0.3-0.4 μm confirmed the observed immature appearance of the nerve supply. Obvious nerve endings were seldom observed and the axons showed no structural association with odontoblasts. The evidence indicates that, although most axons terminate near the incisal end of the tooth, no specific structure is supplied. The qualitative features of the axons do not suggest autonomic function; however, they are consistent with a sensory role.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001600207
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  • 7
    Electronic Resource
    Electronic Resource
    An investigation of lymphatic vessels in the feline dental pulp (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 187 (1990), S. 247-253 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The existence of lymphatic vessels in the dental pulp has been a matter of continuing controversy. We have now used light microscopy to examine semithin transverse sections of perfusion-fixed incisors and canines in cats. Lymphatics were found in all the teeth studies. In most teeth they were present in the coronal, middlel, and apical regions of the pulp; but in a few they were lacking coronally and in the middle. Within individual teeth, lymphatics were found in the subodontoblastic zone or more centrally in the pulp; but none were found in the odontoblast layer or in the pulp horns.Vessels located by light microscopy were subsequently examined by transmission electron microscopy. Their ultrastructural features were typical of lymphatics and included irregular, attenuated endothelium with adjacent cells joined in different ways. Occasional gaps connected the extracellular spaces with their lumens, and abluminal endothelial projections appeared to form open and bulbs. There was very little basement membrane, but anchoring filaments were found near the abluminal surface of the endothelium and near collagen fibrils.The total cross-sectional area of lymphatic vessels was measured in semithin sections and, with pulp area, increased from the coronal region to the middle. However, both areas decreased from the middle to the apical region suggesting either that lymph flows faster as it reaches the formens of the apical delta or that some vessels leave the tooth through lateral root canals.Using the methods of light and transmission electron microscopy, therefore, we have shown that pulp lymphatic vessels exist. Questions remain, however, about their distribution within teeth, variations between teeth, and routes of exit from teeth.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001870304
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  • 8
    Electronic Resource
    Electronic Resource
    Interodontoblastic collagen (von Korff fibers) and circumpulpal dentin formation: An Ultrathin serial section study in the cat (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 191 (1991), S. 67-73 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The collagenous fibers of von Korff pass from the dentin matrix between the odontoblasts into the dental pulp. Although collagen fibrils are known to be present between odontoblasts, the existence of von Korff fibers has remained controversial. This may be because their continuity between the dentin matrix and the pulp has not been demonstrated ultrastructurally.In this study we have examined the odontoblast layer in the middle to apical regions of perfusionfixed permanent canine teeth of cats by using transmission electron microscopy. Ultrathin sections of demineralized specimens revealed frequent bundles of collagen fibrils (1) entering the odontoblast layer from the predentin, (2) present between odontoblst cell bodies, and (3) passing form between the odontoblasts into the pulp.The question of continuity of these bundles from the predentin, across the odontoblast layer into the pulp was examined in ultrathin serial sections. Unbroken continuity of a collagen bundle from the predentin between the odontoblasts into the pulp was established in a reconstruction of one series of 22 serial sections and was very strongly suggested by a number of other series in which the numbers of available sections restricted their full visibility.This investigation has shown, therefore, that classical von Korff fibers are present and that these fibers are present in fully erupted teeth with closed apices, i.e., at a time when secondary circumpulpal dentinogenesis is in progress.The findings call for a reexamination of the question of von Korff fibers during mantle dentinogenesis and primary circumpulpal dentinogenesis. Resolution of their existence at the earlier stages of dentinogenesis should be possible by using the ultrathin serial-sectioning technique.
    Additional Material: 26 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001910107
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