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  • 1
    Electronic Resource
    Electronic Resource
    The relationship between the edge of the chick blastoderm and the vitelline membrane (1969)
    Springer
    Development genes and evolution 163 (1969), S. 113-121 
    Details
    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung l. Der Rand des Hühnchen-Blastoderms wurde gefilmt während der Migration über die innere Oberfläche des Dottermembrans. Dabei wurden „ruffled membranes“ beobachtet, die den vonAbercrombie undAmbrose beschriebenen entsprechen. 2. „Ruffled membranes“ wurden im Transmissions- und auch im Raster-Elektronenmikroskop untersucht. Sie sind sichtbar als breite, abgeflachte Fortsätze, die nahe an der inneren Oberfläche des Dottermembran kleben. 3. Die innere und äu\ere Oberfläche des Dottermembran und auch die endodermale Oberfläche des Area Opaca, wurden im Raster-Elektronenmikroskop untersucht.
    Notes: Summary 1. The edge of the chick blastoderm has been filmed as it migrated over the inner surface of the vitelline membrane. Ruffled membranes are described, comparable to those reported byAbercrombie andAmbrose for other types of cells growing in tissue culture. 2. The ruffled membranes, which have been examined both by scanning and transmission electron microscopy, are visible as broad, flattened processes which adhere closely to the inner surface of the vitelline membrane. 3. The inner and outer surfaces of the vitelline membrane, and the endodermal surface of the area opaca, have also been examined by scanning electron microscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00579315
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  • 2
    Electronic Resource
    Electronic Resource
    Human cranial bone structure and the healing of cranial bone grafts: a study using backscattered electron imaging and confocal microscopy (1990)
    Springer
    Anatomy and embryology 181 (1990), S. 235-251 
    Details
    ISSN: 1432-0568
    Keywords: Human cranial bone ; Bone growth ; Bone grafts ; Back-scattered electron imaging ; Confocal microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study explored the microstructure of human cranial bone at different ages, and the survival, remodelling and modelling of cranial bone grafts. A combination of reflection and fluorescence confocal optical microscopy and scanning electron microscopy in the backscattered electron imaging mode was employed to examine highly polished block faces of plastic-embedded bone fragments as harvested for grafting, or recovered after a period in situ as a graft. The methods enabled remarkably detailed information on bone content, maturation and turnover to be gleaned from tiny scraps of bone. Microfractures in the harvested bone were repaired at the graft site, with welding of old and new bone indicating revascularization. Human cranial bone grafts successfully stimulated bone cell differentiation, supported new bone formation on resorbed and unresorbed surfaces, and underwent bone turnover. The type and organization of new bone reflected the growth rate and maturation of the graft rather than the age of the patient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00174618
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  • 3
    Electronic Resource
    Electronic Resource
    Three-dimensional photographic study of cancellous bone in human fourth lumbar vertebral bodies (1994)
    Springer
    Anatomy and embryology 189 (1994), S. 259-274 
    Details
    ISSN: 1432-0568
    Keywords: Bone ; Cancellous ; Trabecular ; Age ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In an analysis of the 3D architecture of cancellous bone, two-dimensional techniques are of limited value. A simple technique employing stereophotographs of whole sections of lumbar vertebrate made possible a detailed description of the 3D structure of the normal fourth lumbar vertebral body and its changes with ageing and osteoporosis. Parallax measurements were used to calculate the real lengths of horizontal trabeculae. The bone presented a continuous spectrum of microstructure, from a honeycomb of tubes, to plates and braces and, finally, fragile rods. A distinct pattern was produced in osteoporotic samples by the removal of horizontal and selected vertical trabeculae followed by a thickening of the remaining vertical trabeculae in the peripheral regions. Very long, thin horizontal trabeculae were formed in all three zones (superior, middle and inferior) during this process. The observation of porotic architecture in intact specimens points to the inadequacy of the clinical criterion of the occurrence of a fracture in judging the osteoporotic state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239013
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  • 4
    Electronic Resource
    Electronic Resource
    Deciduous enamel defects in low-birth-weight children: correlated X-ray microtomographic and backscattered electron imaging study of hypoplasia and hypomineralization (1994)
    Springer
    Anatomy and embryology 189 (1994), S. 375-381 
    Details
    ISSN: 1432-0568
    Keywords: Enamel hypoplasia ; Hypomineralization ; Low birth weight ; Backscattered electron imaging ; X-ray microtomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Enamel does not remodel, and disturbances occurring during development may remain in the tooth as a permanent record of the upset. Mineralization in prenatal and postnatal deciduous enamel was studied in the shed deciduous incisors of low-birth-weight (LBW: 〈 2kg) children. The specific objective was to gain further insight into the mechanism of formation of developmental defects of enamel. Sections at a resolution of 22–40 μm were reconstructed using X-ray microtomography (μCT) giving absolute measurements of linear absorption coefficient for AgKα radiation. Detail to ca. 1 μm resolution was obtained using automated, digital backscattered electron (BSE) imaging of PMMA-embedded material. Matching the histograms of BSE and μCT images made possible the calibration of the mean atomic number-dependent signal in the BSE images. The comparison of abnormal, affected enamel regions and post-recovery, normal, unaffected regions could be made in the same teeth, since these zones were easily recognized from the distribution of hypoplasia and hypomineralization. The μCT values, converted to calculated mineral densities, ranged from 2.3 g cm-3 to 2.6 g cm-3 in LBW hypoplastic, and between 2.65 and 2.78 g cm-3 in control primary enamel and post-defect, post-natal LBW enamel. Hypoplasia with or without minimal hypomineralization indicated recovery of the ameloblasts in the maturation phase. Disturbance during late matrix formation and early maturation resulted in hypoplasia and hypomineralization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185432
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  • 5
    Electronic Resource
    Electronic Resource
    Dependence of rate of physical erosion on orientation and density in mineralised tissues (1984)
    Springer
    Anatomy and embryology 170 (1984), S. 57-62 
    Details
    ISSN: 1432-0568
    Keywords: Airpolishing ; Orientation effects ; Enamel ; Dentine ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Bone, dentine and enamel samples were treated with a gas-propelled jet of an abrasive, NaHCO3, which is physically much softer than any of these tissues in their fully mineralised condition. It was nevertheless found that they are all eroded by this treatment, which can therefore be used as a new kind of qualitative test of physical properties relating to wear resistance. General correlations were found between both degree of mineralisation and between structure orientation and erosion rate, surface-parallel-feature zones being worn more rapidly. Bone domains with surface-parallel collagen were eroded faster than those with perpendicular lamellae even if they were more densely mineralised. Rates of dentine wear depended on both density and tubule orientation, with peritubular zones and better mineralised incremental layers being more resistant. Enamel tufts wear more rapidly than the surrounding well mineralised regions. Enamel diazones wear less than parazones (areas with surface parallel prisms). At the prism scale, enamel is removed more rapidly near prism boundary discontinuities and in tubular enamel, at tubule walls. As regards the common orientation dependent effects seen in these three tissues, a cohesive explanation would be that structure discontinuities can be better exploited in a wear process if they allow cleavage from the surface; which tendency will increase with parallelism to the surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319458
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  • 6
    Electronic Resource
    Electronic Resource
    Survival and resorptive activity of chick osteoclasts in culture (1986)
    Springer
    Anatomy and embryology 174 (1986), S. 265-275 
    Details
    ISSN: 1432-0568
    Keywords: Bone ; Resorption ; Dentine ; Longevity of osteoclasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Previous studies have shown that osteoclasts obtained from chopped bones resorb surrogate calcified tissue substrata in vitro. These cultures contained all bone and marrow cell type pooled together. We have now parted the marrow from the bone and cultured the cells from the two fractions separately: on both resorbable substrates and on plastic in order to test their longevity in culture and ability to resorb following trypsinisation. Marrow-fraction, bone-fraction or whole bone derived cells were harvested from prehatch chick long bone shafts after removing the periosteum; seeded on sperm whale dentine (SWD) slices or plastic dishes and cultured continously, or trypsinised and reseeded on to fresh substrata at weekly or half-weekly intervals. Observations were made by light microscopy and SEM. Many multinucleate cells were observed in the marrow fraction immediately after settling, deriving presumably from poorly adherent osteoclasts, next to bone, which had not been resorbing at the time of harvesting. By three days in culture on plastic, multinucleate cells were very large both in terms of plant extent and nuclear number: cell fusion occurred between osteoclasts and between osteoclasts and small, round uninuclear cells. SWD was extensively resorbed. The adherence of the osteoclasts was greater (a) to plasuc upon trypsinisation than that of the other cells; and (b) to SWD than to plastic, particularly if the cells were resorbing. Trypsinised cells regained their resorptive capacity after seeding on to new SWD, but only for 1 or 2 treatments. Bone derived cells were similar to the marrow cultures, except for the much higher proportion of other bone cell types. Trypsinisation caused a higher proportional loss of multinucleate cells from both SWD and plastic. Resorption was still occurring at 6 weeks in all cultures. A wide diversity existed in the shapes, depths, plan areas and volumes of the resorption pits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00824342
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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Simulation of bone resorption-repair coupling in vitro (1994)
    Springer
    Anatomy and embryology 190 (1994), S. 339-349 
    Details
    ISSN: 1432-0568
    Keywords: Osteoclasts ; Osteoblasts ; Resorption ; Remodelling ; Dentine ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the normal adult human skeleton, new bone formation by osteoblasts restores the contours of bone surfaces following osteoclastic bone resorption, but the evidence for resorption-repair coupling remains circumstantial. To investigate whether sites of prior resorption, more than the surrounding unresorbed surface, attract osteoblasts or stimulate them to proliferate or make new matrix, we developed a simple in vitro system in which resorption-repair coupling occurs. Resorption pits were produced in mammalian dentine or bone slabs by culturing chick bone-derived cells on them for 2–3 days. The chick cells were swept off and the substrata reseeded with rat calvarial osteoblastic cells, which make bone nodules in vitro, for periods of up to 8 weeks. Cell positions and new bone formation were investigated by ordinary light microscopy, fluorescence and reflection confocal laser microscopy, and SEM, in stained and unstained samples. There was no evidence that the osteoblasts were especially attracted to, or influenced by, the sites of resorption in dentine or bone before cell confluence was reached. Bone formation was identified by light microscopy by the accumulation of matrix, staining with alizarin and calcein and by von Kossa's method, and confirmed by scanning electron microscopy (SEM) by using backscattered electron (BSE) and transmitted electron imaging of unembedded samples and BSE imaging of micro-milled embedded material. These new bone patches were located initially in the resorption pits. The model in vitro system may throw new light on the factors that control resorption-repair coupling in the mineralised tissues in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00187292
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  • 9
    Electronic Resource
    Electronic Resource
    Functional associations between collagen fibre orientation and locomotor strain direction in cortical bone of the equine radius (1993)
    Springer
    Anatomy and embryology 187 (1993), S. 231-238 
    Details
    ISSN: 1432-0568
    Keywords: Bone ; Collagen ; Orientation ; In vivo strain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A novel technique for determining the collagen fibre orientation pattern of cross-sections of cortical bone was used to study mid-diaphyseal sections from the equine radius. Several in vivo strain gauge studies have demonstrated that this bone is loaded in bending during locomotion in such a way that the cranial cortex is consistently subjected to longitudinal tensile strains and the caudal cortex to longitudinal compressive strains. Twenty-three radii from 17 horses were studied. All the bones obtained from adult horses exhibited a consistent pattern of collagen fibre orientation across the cortex. The cranial cortex, subjected to intermittent tension, and the lateral and medial cortices, through which the neutral axis passes, contained predominantly longitudinally oriented collagen fibres. The caudal cortex, subjected to longitudinal compression during life, contained predominantly oblique/transverse collagen. This pattern was less evident in bones from foals. Microscopic analysis of the bones studied showed that primary lamellar bone was composed of predominantly longitudinal collagen fibres, irrespective of cortex. However, there was a strong relationship between cortical location and fibre orientation within remodelled bone. Secondary osteons which formed in the caudal (compressive) cortex contained predominantly oblique/transverse collagen, while those which formed elsewhere contained longitudinal collagen. This observation explained the developmental appearance of the characteristic macroscopic pattern of collagen fibre orientation across the whole cortex in the adult. These findings provide evidence for the existence of a relationship between the mechanical function of a bone with its architecture, and now demonstrate that it extends to the molecular level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195760
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  • 10
    Electronic Resource
    Electronic Resource
    Mechanical implications of collagen fibre orientation in cortical bone of the equine radius (1993)
    Springer
    Anatomy and embryology 187 (1993), S. 239-248 
    Details
    ISSN: 1432-0568
    Keywords: Collagen orientation ; Bone ; Stress ; Strain ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Mechanical test specimens were prepared from the cranial and caudal cortices of radii from eight horses. These were subjected to destructive tests in either tension or compression. The ultimate stress, elastic modulus and energy absorbed to failure were calculated in either mode of loading. Analysis was performed on the specimens following mechanical testing to determine their density, mineral content, mineral density distribution and histological type. A novel technique was applied to sections from each specimen to quantify the predominant collagen fibre orientation of the bone near the plane of fracture. The collagen map for each bone studied was in agreement with the previously observed pattern of longitudinal orientation in the cranial cortex and more oblique to transverse collagen in the caudal cortex. Bone from the cranial cortex had a significantly higher ultimate tensile stress (UTS) than that from the caudal cortex (160 MPa vs 104 MPa; P〈0.001) though this trend was reversed in compression, the caudal cortex becoming relatively stronger (185 MPa vs 217 MPa; P〈0.01). Bone from the cranial cortex was significantly suffer than that from the caudal cortex both in tension (22 GPa vs 15 GPa; P〈0.001) and compression (19 GPa vs 15 GPa; P〈0.01). Of all the histo-compositional variables studied, collagen fibre orientation was most closely correlated with mechanical properties, accounting for 71% of variation in ultimate tensile stress and 58% of variation in the elastic modulus. Mineral density and porosity were the only other variables to show any significant correlation with either UTS or elastic modulus. The variations in mechanical properties around the equine radius, which occur in close association with the different collagen fibre orientations, provide maximal safety factors in terms of ultimate stress, yet contribute to greater bending of the bone as it is loaded during locomotion, and thus lower safety factors through the higher strains this engenders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195761
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