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  • Ultrastructure  (805)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 10 (1972), S. 38-48 
    ISSN: 1432-0827
    Keywords: Bivalve ; Molluse ; Shell ; Carbonates ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La technique du bombardement à l'aide d'ion d'argon est utilisée pour réduire l'épaisseur de la coquille de carbonate de calcium des bivalvesMytilus etMercenaria pour examen au microscope électronique par transmission et en diffraction électronique; une comparaison est réalisée à l'aide de répliques simples, servant de témoins. Les résultats obtenus confirment les études antérieures de répliques et de microscopie par balayage. De plus, une structure “aérée” est mise en évidence dans la coquille des aragonites, et surtout dans le nacre deMytilus. Cette structure est interprêtée comme un artefact induit par la chaleur, formé par l'inclusion d'eau et de matériel organique, interprétation qui concorde avec les études chimiques et de microscopie électronique.
    Abstract: Zusammenfassung Die Beschießung mit Argonionen wurde angewendet, um die Dicke von Calciumcarbonat-Schalen der zweischaligen MuschelnMytilus undMercenaria zu reduzieren. Diese Technik erlaubte die Ausführung von Transmissions-Elektronenmikroskopie und Elektronendiffraktion, wobei gleiche Proben nach einer bereits bestehenden Methode vorbereitet und als Kontrollen herangezogen wurden. Es wurden zusätzliche Resultate zu den Muschelstruktur-studien erhalten, welche früher publizierte Arbeiten unterstützen, die mit der Abklatschmethode und der Raster-Elektronenmikroskopie ausgeführt worden waren. Zusätzlich wurde eine „schaumartige” Struktur der Muschelaragoniten, besonders im Perlmutter vonMytilus, beobachtet. Da es sich um ein durch Hitze verursachtes Artefakt handelt, wird diese Struktur als Einschlüsse von Wasser und organischem Material interpretiert, was den Befunden von verschiedenen veröffentlichten chemischen und elektronenmikroskopischen Arbeiten entspricht.
    Notes: Abstract Use is made of the argon ion-bombardment technique to reduce the thickness of calcium carbonate shells of the bivalvesMytilus andMercenaria for transmission electron microscopy and electron diffraction, with comparison of single-stage replicas of similar specimens serving as controls. As an additional approach to shell structure studies, it gives results which support earlier published work with both replicas and scanning microscopy. In addition, a “frothy” structure is detected in the shell aragonites, especially inMytilus nacre. As a heat-induced artifact, it is interpreted as representing trapped water and organic material inclusions, an interpretation consistent with several published chemical and electron microscope studies.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 10 (1972), S. 216-222 
    ISSN: 1432-0827
    Keywords: Ultrastructure ; Callus ; Osteoclast ; Endocytosis ; Lysosomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La bordure en brosse des ostéoclastes de cals de fractures de rats présente des plissements complexes de la membrane cytoplasmique formant des canaux étroits. L'absorption d'un produit exogène opaque aux électrons (des macromolécules de dioxyde de thorium) s'effectue par l'intermédiaire de ces canaux, par un «courant» membranaire. Les contenus des canaux sont transférés à des lysosomes («granules spécifiques»), situés sous la bordure en brosse. Dans des «régions de transition», adjacentes à cette dernière, l'absorption de dioxyde de thorium se fait par «vésiculation membranaire» (endocytose classique).
    Abstract: Zusammenfassung Der gekrauste Rand der Osteoklasten im Frakturcallus von Ratten besteht aus komplexen Einstülpungen der Plasmamembran, die enge Kanälchen bildet. Die Absorption einer exogenen, elektronisch dichten Verbindung, Thoriumdioxyd, erfolgt durch diese Kanäle, offenbar durch einen „Membranfluß”. Der Inhalt der Kanäle wird zu den Lysosomen („spezifische Granula”) geführt, welche unter dem gekrausten Rand liegen. In „Übergangsgebieten”, welche sich neben dem gekrausten Rand befinden, scheint die Aufnahme der Thoriumdioxydpartikel durch „Bläschenbildung in der Membran” (konventionelle Endocytose) stattzufinden.
    Notes: Abstract The ruffled border of osteoclasts in the fracture callus of rat consists of complex infoldings of the plasma membrane forming narrow channels. Absorption of an exogenous, electron-dense compound, thorium dioxide, has been shown to take place via these channels, apparently through “membrane flow”. The contents of the channels are transferred to lysosomes (“specific granules”) located subjacent to the ruffled border. In “transitional regions” adjacent to the ruffled border, uptake of thorium dioxide particles appeared to occur through “membrane vesiculation” (conventional endocytosis).
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 12 (1973), S. 259-279 
    ISSN: 1432-0827
    Keywords: Osteocyte ; Calvarium ; Histology ; Development ; Calcium ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des cartes tissulaires ainsi que les caractéristiques et propriétés cellularires ont été relevées au cours d'une étude de microscopie optique du développement de la calotte cranienne de souris, avant la naissance, jusqu'au 26ème jour. Les population d'ostéocytes de moitiés droite et gauche de ces calottes sont semblables, mais décroissent avec le temps dans un volume donné. De petites plages limitées de matrice osseuse se colorent pour le phosphate (ou carbonate) de façon plus nette que la matrice environnante, qui se colore légèrement après coupe. Les divers types ostéocytaires se distinguent par les réactions histochimiques du calcium et du phosphate, qui sont associés dans les cellules osseuses de façon complexe, variant dans le temps et la localisation. Ces deux constituants ne sont pas toujours présent dans les cellules des diverses régions, ou dans la même localisation dans un type cellulaire donné. En tenant compte des changements visible dans les divers types cellulaires avec le temps, dans des régions données, une hypothèse de “charge” et “décharge” cellulaire est émise.
    Abstract: Zusammenfassung Anläßlich einer mikroskopischen Studie über die Entwicklung des Mäuse-Calvariums von der Pränatalperiode bis zu 26 Tagen nach der Geburt wurden auch die Gewebetopographie sowie die Charakteristica und Eigenschaften der Zellen aufgezeichnet. Die Osteocyten-populationen in der linken und rechten Hälfte des Calvariums waren sich gleich, nahmen jedoch bei einem gegebenen Volumen mit der Zeit ab. Kleine isolierte Stellen von Knochen-matrix konnten leichter auf Ph sphat (oder Carbonat) angefärbt werden, als die umgebende Matrix, welche sich wohl am Schnitt, nicht aber am ganzen Stück färben ließ. Die verschiedenen Typen von Osteocyten wurden aufgrund histochemischer Calcium- und Phosphat-reaktionen bestimmt. Calcium und Phosphat waren innerhalb der Knochenzellen auf komplexe Art miteinander verbunden, die je nach Zeit und Lagerung unterschiedlich war. Zellen in abgetrennten Bereichen enthielten nicht immer Calcium und Phosphat und beide waren bei einer bestimmten Zellenart auch nicht immer am gleichen Ort abgelagert. Aufgrund der an ausgewählten Stellen beobachteten, zeitlich bedingten Veränderungen innerhalb der verschiedenen Zelltypen wird vorgeschlagen, daß es sich dabei um eine Sequenz von “Ladung” und “Entladung” der Zellen handelt.
    Notes: Abstract Tissue maps, and cell characteristics and properties were recorded in a study under the optical microscope of the development of the mouse calvarium from pre-natal to 26 days. Osteocyte populations in left and right halves of the calvarium were similar, but decreased with time for a given volume. Small isolated areas of bone matrix stained for phosphate (or carbonate) in a more readily available form from that in the surrounding matrix, which could be stained after sectioning but failed to stain in bulk. Osteocyte types were defined on the basis of histochemical methods for calcium and phosphate, which were associated inside bone cells in a complex manner, varying with time and position. The calcium and phosphate were not always present within the cell in discrete regions and were not always present in the same place in a given cell type. On the basis of a study of changes in cell types with time in selected sites a sequence of “loading” and “unloading” is proposed.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 16 (1974), S. 209-217 
    ISSN: 1432-0827
    Keywords: Mucopolysaccharides ; Collagen ; Calvarium ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Mucopolysaccharides (MPS) and collagen have been analyzed in different types of cartilage and some other tissues at various stages of prenatal and postnatal human development. The concentration of the chondroitin sulfate-type MPS increased from the 38th embryonal day, the 6-sulfate exceeding in amount the 4-sulfate. The increase in collagen concentration was accompanied by a decrease in the proportion of neutral salt-soluble collagen. There was no accumulation of chondroitin sulfates in the calvaria. A maximal concentration of MPS of a low molecular weight occurred in the skin and in the ear pinna after the 10th prenatal week. Postnatally, the MPS-concentration in the iliac crest and in the tibial articular cartilages decreased gradually, the highest values being reached in the newborn; the collagen-concentration showed an approximately reciprocal course.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 25 (1978), S. 145-159 
    ISSN: 1432-0827
    Keywords: Bird egg shell ; Ultrastructure ; Calcification ; Electron diffraction ; Microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The egg-shell of Japanese quail was studied by several techniques. Semithin sections (1μm thick) of non-decalcified shell were observed by normal and polarized light microscopy. Thin sections of non-decalcified shell, examined by transmission electron microscopy, permitted us to observe the forms and dimensions of crystals of calcite within different layers of the shell: mammilary layer, layer of cones, palissade layer and surface crystal layer. There appears to be two distinct zones in the layer of cones as well as in the superficial crystal layer. Electron microdiffraction revealed the orientation of calcite crystals in the columns. Some crystal defects (twins?) were described and the possibility of their artefactual formation during ultramicrotomy is discussed. Localization of Ca, Mg, P and S were made by X-ray microanalysis of semithin sections. This technique shows that shell membranes, and chiefly the true cuticle, are also mineralized but, in these layers, minerals are not crystallized. Otherwise the distribution of Mg is not uniform throughout the shell thickness; it is less concentrated in the external zone of the layer of cones. These results together with observation of developing shells by scanning electron microscopy allowed us to propose a scheme for shell organization of the quail egg. This organization was related with decalcification which occurs during hatching.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 24 (1977), S. 215-222 
    ISSN: 1432-0827
    Keywords: Mineralization ; Osteodentin ; Intracellular ; Ultrastructure ; Microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Newly formed osteodentin obtained from the anterior extremities of fetal or young rat incisors was observed by means of electron microscopy and electron probe X-ray microanalysis. Cells related to osteodentin formation frequently showed membrane bound intracellular bodies containing varying amounts of fine, needle-shaped crystals, which were identified as apatite. The intracellular clusters of apatite crystals were extruded from the cells through membrane fusion or cellular degeneration. These extracellular clusters seemed to be gradually incorporated into the mineralizing collagenous matrix, which developed around them. Frequent occurrence of dense, dotshaped or filamentous profiles suggested that the dense bodies seen in the perinuclear regions or in the Golgi area were the sites of crystal formation. Energy dispersive X-ray point analysis showed that the intracellular or extracellular apatite clusters contained sulfur in a concentration higher than was present in the mineralizing collagenous matrix. Furthermore, wave dispersive X-ray line analysis showed that the concentration of sulfur was higher in the osteodentin matrix than in the dentin matrix. The sulfur detected is presumed to be contained in acid mucopolysaccharides, which were distributed more heavily in the osteodentin matrix than in the dentin matrix. On the basis of these data, it was concluded that the unique chemical and structural characteristics of the osteodentin result primarily from the incorporation of apatite clusters of intracellular origin and associated acid mucopolysaccharides.
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  • 7
    ISSN: 1432-0827
    Keywords: Bone resorption ; Osteogenesis ; Fish bone ; Osteocytes ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The comparative ultrastructure of fish bone osteogenesis and resorption induced by scale removal was described in the osteocytic (cellular-boned)Carassius auratus and the anosteocytic (acellular-boned)Tilapia macrocephala. Osteocytes, present in osteocytic bone, were lacking in anosteocytic bone. In osteocytic bone the osteoblast secreted a collagenous preosseous matrix in which it became enmeshed and then was termed a preosteocyte. When the preosseous matrix mineralized, the preosteocyte was termed an osteocyte and was completely surrounded by bone. In anosteocytic bone the osteoblasts receded from the mineralizing front and never became trapped as osteocytes. During resorption, types A and B resorptive cells, present in both bone types, invaded the matrix and demineralized the osseous zone. These cells were characterized by large amounts of granular endoplasmic reticulum and intracellular inclusions containing crystal-like material. Although functionally similar to mammalian osteoclasts, these cells lacked a characteristic ruffled border and were not multinucleated. The osteocytes of cellular bone did not appear to be involved during demineralization.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 9 (1972), S. 296-309 
    ISSN: 1432-0827
    Keywords: Osteoclasts ; Enzyme ; Parathyroid ; Microdissection ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une nouvelle méthode d'isolement d'ostéoclastes est mise au point pour des analyses biochimiques et de microscopie électronique. Pour isoler les cellules par microdissection, des empreintes d'os métaphysaire sont utilisées. Cette méthode, supérieure aux coupes d'os, permet une meilleure préservation cytologique et enzymatique et permet d'obtenir des cellules totales plus faciles à manipuler, avec des résultats plus reproductibles. Par analyse planimètrique de cellules isolées, colorées histochimiquement, il apparait que les ostéoclastes constituent plus de 90% de la masse de l'échantillon. Les concentrations de la phosphatase acide et de certaines enzymes, liées au nucléotide pyridinique, entrant dans le métabolisme de l'acide citrique, sont déterminées dans des échantillons d'ostéoclastes, pesant de 0,2 à 2,0 μg, isolés à partir de rats normaux et parathyroidectomisés. L'activité en aconitase, mesurée en direction de la transformation de citrate en isocitrate, est de 0,5–0,8 M/Kd/H, la plus faible des activités étudiées. Les activités en GDH et NADP-ICDH sont 5 à 10 fois supérieures que celle de l'aconitase, mais seulement un dixième à un tiers de celle de la phosphatase acide, de la déshydrogénase lactique ou malique.
    Abstract: Zusammenfassung Es wird eine neue Technik beschrieben, welche die Isolierung von Osteoklasten für biochemische und elektronenmikroskopische Untersuchungen ermöglicht. Als Ausgangsmaterial zur Zellisolierung wurden Abstriche von Metaphysenknochen benützt. Die Verwendung von Abstrichen bietet gegenüber Knochenschnitten wichtige Vorteile, wie z.B. eine bessere Erhaltung der cytologischen und enzymatischen Eigenschaften sowie die Gewinnung von unverletzten Zellen, welche leichter verarbeitet werden können und besser reproduzierbare Daten ergeben. Durch planimetrische Analyse der histochemisch gefärbten Ausstriche von isolierten Zellen konnte nachgewiesen werden, daß die Osteoklasten über 90% des gesamten Probenmaterials ausmachen. Die Mengen verschiedener Enzyme, welche an Pyridinnukleotid gebunden und am Citronensäuremetabolismus beteiligt sind, sowie der sauren Phosphatase wurden in Osteoklastenproben bestimmt, welche ein Gewicht von 0,2–2,0 μg hatten und aus Knochen von normalen und mit Parathyroidextrakten behandelten Ratten isoliert worden waren. Die Aktivität der Aconitase, welche in der Richtung von Citrat zu Isocitrat gemessen wurde, war mit 0,5–0,8 M/Kd/H die niedrigste aller untersuchten Aktivitäten. Die Aktivitäten der GDH und der NADP-ICDH waren 5–10mal höher als jene der Aconitase, entsprachen jedoch nur einem Zehntel bis einem Drittel derjenigen der sauren Phosphatase, der Laktat- oder der Malatdehydrogenase.
    Notes: Abstract A new method is described by which osteoclasts can be isolated for biochemical and electron microscopic analyses. As a source of cells for isolation by microdissection, imprints of metaphyseal bone were used. The use of imprints provides important advantages over bone sections, including a higher degree of cytologic and enzymatic preservation, and the delivery of whole cells which are more readily manipulated and which yield data that are more readily reproduced. By planimetric analysis of the histochemically-stained isolated cell samples, it was shown that osteoclasts represent over 90% of the sample mass. The levels of several of the pyridine nucleotide-linked enzymes involved in citric acid metabolism, as well as acid phosphatase, were determined in osteoclast samples weighing 0.2 to 2.0 μg isolated from normal and parathyroid-treated rats. Aconitase activity measured in the direction of citrate to isocitrate was 0.5–0.8 M/Kd/H, the lowest of the activities studied. The activities of GDH and NADP-ICDH were 5 to 10 times higher than that of aconitase but only a tenth to a third that of acid phosphatase, lactic or malic dehydrogenase.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 7 (1971), S. 191-200 
    ISSN: 1432-0827
    Keywords: Serpulid ; Polychaete ; Hydroxyapatite ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Un petit groupe de cellules épithéliales de la surface antérieure du col du serpulidePomatoceros caeruleus contient des vacuoles, remplies de matériel cristallin. Les cristaux présenttent des aspects rhomboédriques ou rectangulaires. La diffraction électronique montre qu'ils sont constitués par de l'hydroxyleapatite et du phosphate de calcium et de magnésium. Les apex des cellules sont bordés de microvillosités. Certaines cellules ont des cils apicaux. Un appareil de Golgi est visible dans le cytoplasme apical. De nombreuses mitochondries sont dissé minées dans le cytoplasme. Le role éventuel de ces cellules, a contenu minéral, dans la mise en réserve de calcium et/ou de phosphore est envisagé.
    Abstract: Zusammenfassung Ein kleiner Zellverband im Epithel der vorderen Oberfläche am Hals des SerpulidsPomatoceros caeruleus enthält membrangebundene Vakuolen, welche mit kristallinem Material gefüllt sind. Die Kristalle haben rhomboide oder rechteckige Formen; mittels Elektronendiffraktion konnte nachgewiesen werden, daß sie aus Hydroxyapatit und Calciummagnesiumphosphat bestehen. Die oberen Enden der Zellen sind von Microvilli eingefaßt. Einige der Zellen haben zudem apikale Zilien. Die Zellen enthalten Golgi-Apparate im apikalen Cytoplasma. Eine große Anzahl von Mitochondrien sind über das, ganze Cytoplasma verteilt. Die mögliche Funktion dieser mineralhaltigen Zellen als Aufbewahrungsorte für Calcium und/oder Phosphor wird besprochen.
    Notes: Abstract A small patch of cells in the epithelium of the anterior surface of the collar of the serpulidPomatoceros caeruleus contains membrane-bound vacuoles filled with crystalline material. The crystals have rhomboidal or rectangular profiles and have been shown by electron diffraction analysis to be composed of hydroxyapatite and calcium magnesium phosphate. The apices of the cells are bordered by microvilli. Some cells also have apical cilia. The cells contain Golgi complexes in the apical cytoplasm. Large numbers of mitochondria are distributed thoughout the cytoplasm. The possible function of these mineral-containing cells as sites for storage of calcium and/or phosphorus is discussed.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 3 (1974), S. 109-113 
    ISSN: 1432-1432
    Keywords: “Custom Fitting” ; Development ; Evolution ; Antibody response ; Genetic Redundancy ; Perturbation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary When the complexity of a developmental system evolves to a certain point, appreciable variation must occur in the process. The problem the biologist faces is whether this point constitutes a limit to the evolution of complexity in developmental systems. If not, what mechanisms are employed to cope with the problem ? The problem—essentially one in “custom fitting” of parts, — and the possible solution(s) to it that have evolved are discussed. The antibody producing system appears to be one that “solves” the custom-fitting problem.
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