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  • Articles  (70)
  • Electron microscopy  (41)
  • Atomic, Molecular and Optical Physics  (29)
  • 1970-1974  (59)
  • 1965-1969  (11)
  • 1960-1964
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  • Articles  (70)
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  • 1
    Electronic Resource
    Electronic Resource
    Inter- and intracisternal elements of the Golgi apparatus (1972)
    Springer
    Cell & tissue research 132 (1972), S. 365-380 
    Details
    ISSN: 1432-0878
    Keywords: Golgi apparatus ; Membranes ; Cross-bridges ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron opaque cross-bridge structures span the inter- and intracisternal spaces and provide membrane-to-membrane connections between adjacent cisternae of dictyosomes of pollen tubes ofClivia andLilium. Additionally, the classic intercisternal rods, characteristic of intercisternal regions near the maturing face of dictyosomes, are connected with the adjacent membranes through similar cross-bridge elements. We suggest that these structural links are responsible for maintaining the flattened appearance of the central parts of Golgi apparatus cisternac as well as for the coherence of cisternae within the stack. Observations on other plant (e.g. microsporocytes ofCanna) and animal cells (e.g. rodent liver and hepatoma cells, newt spermatocytes) show that such an array of membrane cross-links is a universal feature of Golgi apparatus architecture. The cross-bridges appear as part of the complex “zone of exclusion” which surrounds dictyosomes, entire Golgi apparatus and Golgi apparatus equivalents in a variety of cell types.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02450714
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  • 2
    Electronic Resource
    Electronic Resource
    Ultrastructural study of arterio-venous anastomoses in gill filaments of Tilapia mossambica (1974)
    Springer
    Cell & tissue research 155 (1974), S. 491-512 
    Details
    ISSN: 1432-0878
    Keywords: Gills ; Tilapia mossambica ; Arterio-venous anastomoses ; Specialized endothelia ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Arterio-venous anastomoses (AVA) in gill filaments of Tilapia mossambica exhibit a distinct polarity. Two different types of highly specialized endothelial cells, both of epitheloid shape, line these vessels: Type I cells, contacting the arterial lumen, are elongated and about two to three times as large as type II endothelial cells. Their surface is increased by tentacular protrusions which reach far into the arterial lumen. Filament whorls forming tubelike structures with centrally located glycogen granules are abundant in these cells. Type II endothelial cells are located proximal to the central venous sinus (CVS). Their less abundant and more electron dense cytoplasm is free of filament whorls. There are also intermediate cell forms at approximately the middle of each anastomosis. Short cell processes protrude from all endothelial cell types into the AVA lumen. Outside the indistinct vascular basement lamina, a layer of cover cells tightly envelopes the AVA. These cells are, however, absent around the part of the AVA adjacent to the CVS. Here the endothelial cells are in immediate contact with the interstitium. Endothelial cells sheathed by cover cells reach the interstitium through basal foot processes. Nerve fibre bundles regularly come into close contact with the AVAs. Possible functions of the AVAs, including osmoreception are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227011
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  • 3
    Electronic Resource
    Electronic Resource
    Dynamics of spermiogenesis in Drosophila melanogaster (1972)
    Springer
    Cell & tissue research 127 (1972), S. 492-525 
    Details
    ISSN: 1432-0878
    Keywords: Spermatozoa ; Drosophila ; Testis ; Fertility ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In Drosophila melanogaster, the cyst cell that surrounds the head region of sperm bundle becomes spheroidal or ellipsoidal and is trapped by the terminal epithelium of the testicular wall during the synchronous coiling of sperm. Extensions of this cyst cell are projected caudally into the interspaces between sperm heads probably to anchor the heads. Coiling of sperm tails is initiated at the head region and proceeds by the progressive retraction of the linear portion from the apical testicular region into the coiled portion at the base. The addition of one turn of coil is accompanied by one full rotation of the sperm bundle. When coiled, normal tails are tightly packed into a hexagonal lattice, and minute tubular structures of about 150 Å in diameter occupy the space between them. Sperm with abnormal tails are separated from those with normal ones and isolated into a separate part of the cyst lumen. Acid phosphatase is involved in the dissolution of the minute tubules for the liberation of sperm from the cyst. Sperm are released leaving the major portion of the cyst cells intact. This portion contains degenerating abnormal tails and the waste products of the individualization process. This detritus is ingested by the terminal epithelium and eventually degenerates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00306868
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  • 4
    Electronic Resource
    Electronic Resource
    Reconstitution of the thymus dependent area in the spleen of lethally irradiated mice (1974)
    Springer
    Cell & tissue research 149 (1974), S. 43-60 
    Details
    ISSN: 1432-0878
    Keywords: Spleen ; Thymus dependent area ; Periarteriolar lymphatic sheath (PALS) ; Interdigitating cell (IDC) ; T-lymphocyte ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary To study the submicroscopical morphology of the microenvironment for T-lymphocytes in the spleen, mice were lethally X-irradiated and injected intravenously with syngeneic thymocytes. 24 hours after cell transfer, small lymphocytes occurred in the thymus dependent area of the spleen: the periarteriolar lymphatic sheath (PALS). They localized preferentially around a special type of mononuclear phagocyte, the Interdigitating Cell (IDC), which is considered to be characteristic for thymus-dependent areas in peripheral lymphoid organs. A close cell contact between both cell types was observed: small lymphocytes protruded into the cytoplasm of the IDC by means of fingerlike protrusions. This type of cell contact seems to induce blast transformation of the lymphoid cells which resulted in the formation of medium sized T-cells. In a control experiment, spleen cells from thymectomized, X-irradiated and bone marrow reconstituted mice were injected intravenously into lethally X-irradiated recipients. These B-lymphocytes, however, were not found to be localized around IDC. They preferentially formed primary follicles at the periphery of lymphocyte-depleted thymus dependent areas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209049
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  • 5
    Electronic Resource
    Electronic Resource
    Dynamics of spermiogenesis in Drosophila melanogaster (1972)
    Springer
    Cell & tissue research 124 (1972), S. 479-506 
    Details
    ISSN: 1432-0878
    Keywords: Spermatozoa ; Drosophila ; Testis ; Fertility ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A morphogenetic process that transforms spermatids from a syncytial state to a state in which each spermatid is invested in its own membrane, is initiated at the head region of the spermatid bundle and traverses through the entire length of the bundle in the testis of Drosophila melanogaster. This process not only eliminates the syncytial bridges between spermatids but also removes unneeded organelles and the excess parts of the nuclear membrane, nucleoplasm and cytoplasm. It also brings about structural modifications to flagellar elements. The propagation of this process is seen as the caudal movement of a fusiform swelling of the spermatid bundle, 100 μ or more in length. Spermatids are individualized in the basal half of the swelling, whereas they remain syncytial in the apical half. The swelling increases its volume as it accumulates cytoplasmic debris while traversing the sperm bundle, from about 15 μ in maximum diameter in the basal testicular region to as large as 30 μ at the apical end where it becomes a bag of wastes. A variation of the process in a mutant stock which is known to inactivate up to half of the products of meiosis is briefly described. The morphological change of interspermatid bridges prior to the individualization is also reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335253
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  • 6
    Electronic Resource
    Electronic Resource
    Bounds for eigenfunctions of one-electron molecular systemsThis work has been supported in part by the NATO Research Grants Program under the number SA5-2-05(170)1757PS and in part by the Aerospace Research Laboratories, Office of Aerospace Research, United States Air Force, Contract numbers AS-7-283 and AS-8-0001. (1969)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 3 (1969), S. 581-586 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This article gives pointwise bounds for the wave functions of one-electron molecular systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560030505
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  • 7
    Electronic Resource
    Electronic Resource
    Membrane junctions between salivary gland cells ofChironomus thummi (1972)
    Springer
    Cell & tissue research 127 (1972), S. 116-126 
    Details
    ISSN: 1432-0878
    Keywords: Cell junctions ; Nexus ; Osmotic effects ; Fixatives ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Speicheldrüsen von Mückenlarven (Chironomus Thummi) haben eine ausgedehnte interzelluläre Kommunikation. In elektronenmikroskopischen Bildern der Speicheldrüsen wurden zwei Arten von interzellulären Verbindungen gefunden, die für die Zellkopplung verantwortlich sein könnten: septate junctions und close membrane junctions. Da die räumliche Ausdehnung der septate junctions viel größer zu sein scheint als die der close junctions, wurden erstere als wahrscheinliche Kopplungsstrukturen angesehen. Es gibt jedoch Hinweise, daß die Strukturen, welche die Zellkopplung bewirken, sehr labil sind. Unter den Faktoren, die zu einer Unterbrechung der zellulären Kommunikationen führen können, sind auch osmotische Effekte. Um mögliche Einflüsse dieser Art auf die Ultrastruktur zu verhindern, wurden die Drüsen für die mikroskopische Inspektion in isoosmotischen Lösungen fixiert. Unter diesen Bedingungen lassen sich ausgedehnte Membrankontakte vom nexus-Typ zwischen den Drüsenzellen erkennen. Ihre Ausdehnung scheint ebenso groß zu sein wie die der septate junctions. Es besteht nach diesen Befunden die Möglichkeit, daß wie in anderen kommunizierenden Zellsystemen, so auch in Speicheldrüsen die interzelluläre Kommunikation durch nexus bewirkt wird.
    Notes: Summary Cells ofChironomus salivary glands communicate through intercellular connections of high permeability. Electron micrographs of salivary glands show two kinds of junctions between the membranes of adjacent cells, which may be responsible for cell coupling: septate junctions and close membrane junctions. A large fraction of lateral cell surfaces is occupied by septate junctions, while the area of close membrane junctions appears to be very small. Consequently septate junctions have been considered as likely sites for intercellular coupling. There are however some indications that intercellular communication is provided by structures which seem to be unstable. As osmotic effects are among the factors which can disrupt cellular communications, we have tried to eliminate possible effects of the fixing solutions on the ultrastructure of intercellular connections by using isoosmotic fixatives. Under these conditions large regions of close membrane junctions of the nexus kind have been observed to occur between gland cells. They are of similar size as septate junctions. It seems to be possible that as in other communicating cell systems nexus could be the sites for intercellular coupling of salivary gland cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582761
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  • 8
    Electronic Resource
    Electronic Resource
    Myelinated nerve cell perikaryon in mouse spinal cord (1972)
    Springer
    Cell & tissue research 128 (1972), S. 135-138 
    Details
    ISSN: 1432-0878
    Keywords: Spinal cord ; Mouse ; Myelinated neuronal soma ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Im Thorakalmark (Hinterhornbereich) einer Wildmaus wurde ein kleines Nervenzellperikaryon beobachtet, das vollständig von einer Markscheide umhüllt war. Die Zahl der Markscheidenlamellen variierte zwischen 7 und 12. An einer Stelle konnte ein sogenanntes inneres Mesoperikaryon nachgewiesen werden. Die Bedeutung dieses zufällig erhobenen Befundes ist vorerst noch offen.
    Notes: Summary In the thoracic cord (posterior horn region) of a wild mouse, we have observed a small nerve cell soma completely enveloped by a myelin sheath. The number of myelin lamellae varied between 7 and 12. In one place, the existence of an inner ‘mesoperikaryon’ could also be shown. The significance of this fortuitous finding has not yet been explained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00306893
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  • 9
    Electronic Resource
    Electronic Resource
    Amöboid bewegliche Pigmentzellen im Epithel des Seeigels Centrostephanus longispinus (1972)
    Springer
    Cell & tissue research 133 (1972), S. 82-102 
    Details
    ISSN: 1432-0878
    Keywords: Echinoidea ; Colour change ; Chromatophores ; Amoeboid movement ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Für den physiologischen Farbwechsel bei Vertebraten und Evertebraten gilt die Vorstellung, daß eine Pigmentbewegung innerhalb einer formkonstanten Zelle stattfindet. Am Seeigel Centrostephanus longispinus wird nun der Nachweis einer amoeboiden Bewegung von Pigmentzellen geführt: Die Epidermis von Centrostephanus enthält große braune Chromatophoren, die bei Belichtung eine Pigmentdispersion, bei Verdunkelung eine Konzentration des Pigments zeigen. Die Chromatophoren sind außerordentlich stark verzweigte Zellen, deren Arme dicht mit Pigmentgrana erfüllt sind. Im geballten Zustand ist die allgemeine Zellform mehr oder weniger ovoid, wobei die Zellarme eingezogen und dicht um die Zellmitte angeordnet sind. Dispersion des Pigments wird hervorgerufen durch Ausstrecken der pigmentierten Zellarme in den Interzellularraum des umgebenden Gewebes. Innerhalb der Zelle werden filamentöse Elemente nachgewiesen, die vermutlich für die Zellbeweglichkeit verantwortlich sind. — Ferner wird der zelluläre Aufbau des Integuments beschrieben.
    Notes: Summary Rapid colour changes in vertebrate and invertebrate species are considered to be due to movement of pigment granules within pigment cells of constant shape. Evidence is presented in this study to show that an amoeboid movement of chromatophores occurs in the epidermis of the Echinoderm Centrostephanus longispinus. The epidermis in this species contains large brown chromatophores, which display a dispersion of pigment on illumination and its concentration on darkening. The chromatophores are extensively branched cells, and their branches are densely packed with pigment granules. In the state of pigment concentration, the shape of the cell is more or less ovoid, and the cell branches are drawn in and closely arranged around the cell centre. Dispersion is attained by a stretching out of the pigmented cell branches into the intercellular spaces of the surrounding tissue. Within the cell, filamentous elements, which may be functional in the motility of the pigment cell, can be demonstrated.—Additionally the cellular composition of the integument is described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307069
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  • 10
    Electronic Resource
    Electronic Resource
    Elektronenmikroskopische Untersuchungen zur funktionellen Morphologie des Tubero-hypophysären Systems der Ratte (1973)
    Springer
    Cell & tissue research 139 (1973), S. 101-148 
    Details
    ISSN: 1432-0878
    Keywords: Infundibulum ; Rat ; Neuro-glial synapses ; Neuro-Vascular contacts ; Corticotropin-Releasing Factor ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung 1. Die Gefäßfortsätze von ependymalen und subependymalen Zellen bilden in der subependymalen Zone und in der Zona interna des Ratteninfundibulum mit Nervenfasern kompakte neuro-gliöse Faserbündel, die sich in der Zona externa aufzweigen. 2. In allen Zonen des Infundibulum kommen zwischen den Nervenfasern und den Gefäßfortsätzen zahlreiche neuro-gliöse Synapsen vor. In den Gefäßfortsätzen fällt die hohe Zahl an Mikrotubuli sowie die zahlreichen, vielgestaltigen Einschlüsse auf. 3. In der subependymalen Zone sind die Interzellularspalten an bestimmten Stellen außerordentlich weit. Sie haben eine kanalartige Beschaffenheit und enthalten feine Bündel von Nervenfasern. 4. Von den lateralen Anteilen des Infundibulum her erreichen Dendriten von Ganglienzellen des Nucleus infundibularis die Mitte des Infundibulum. In dieser Region sind axodendritische Synapsen anzutreffen. 5. Morphometrische Analysen der Nervenfaserendigungen der Zona externa von Normaltieren zeigen, daß die prozentuale Verteilung der nach Granulagröße differenzierten Nervenfaserklassen für Mitte und Seite der Zona externa etwa gleich ist. Zwischen der Größe der Elementargranula und der Anschnittfläche der zugehörigen Nervenfasern besteht eine direkte Beziehung. 6. Die Nervenfaserendigungen erreichen die Basalmembran des perikapillären Raumes fast ausschließlich im Bereich von gefäßwärts gerichteten Vorwölbungen der Zona externa. Das Ausmaß, in dem Nervenfasern im Vergleich zu den Gefäßfortsätzen von Ependymund Gliazellen den perivaskulären Raum erreichen, ist medial weitaus größer als lateral. 7. Bei bilateral adrenalektomierten Ratten nimmt in bestimmten, vorwiegend lateral gelegenen Nervenfasern die Zahl und Größe der Elementargranula in Abhängigkeit von der Überlebensdauer zu. Dies dürfte auf eine verstärkte Synthese und Speicherung von Corticotropin-Releasing Factor in diesen Nervenfasern zurückzuführen sein. Gegenüber dem Normalbefund ist die neurohämale Kontaktfläche erheblich vergrößert. Der perivaskuläre Raum enthält zerfallene Nervenfaserteile, die durch Bindegewebszellen phagocytiert werden. Diese Veränderungen dürften durch eine unter Versuchsbedingungen verstärkte Wachstumstendenz der Nervenfasern in Richtung auf die Blutgefäße und durch eine Abschnürung der Nerven-faserendigungen ausgelöst werden.
    Notes: Summary 1. In the subependymal and internal zones of the rat median eminence nerve fibres and vascular processes of ependymal and subependymal cells form neuro-glial bundles. They branch in the external zone. 2. In all these three zones of the infundibulum numerous neuro-glial synapses are found between nerve fibres and vascular processes of glial cells. The vascular processes contain a high number of microtubules as well as polymorphous granular inclusions. 3. In certain regions of the subependymal layer the intercellular spaces are enlarged. They form channel-like spaces containing small bundles of delicate nerve fibres. 4. Nerve cells of the infundibular nucleus located in the lateral parts of the infundibulum send dendrites to the medial parts of the infundibulum. In this area axo-dendritic synapses are found. 5. For morphometric analysis, the nerve fibres of the external zone were classified according to the diameter of their granules. It is shown that in the different regions of the external zone the distribution of the various types of nerve fibre is similar. Moreover it can be seen that a direct correlation exists between the size of the sectional plane of a given nerve fibre and the size of the granules it comprises. 6. Nerve fibre endings abutting on the basement membrane of the pericapillary space are mostly found in bulb-like protrusions of the external zone. The extent to which nerve fibres reach the perivascular space—as compared with the vascular processes of ependymal and glial cells—is higher in the medial than in the lateral parts of the infundibulum. 7. In bilaterally adrenalectomized rats the number and diameter of elementary granules increases in nerve fibres located laterally. This increase is directly related to the survival time and may be due to an enhanced synthesis and storage of Corticotropin-Releasing Factor in these nerve fibres. Compared with the findings in untreated animals the neurohemal contact area is significantly enlarged. The perivascular space contains degenerating nerve fibres which are undergoing phagocytosis by connective tissue cells. It is assumed that these alterations are due to the increased growth of nerve fibres towards the vessels of the “Mantelplexus”, and that, following adrenalectomy, this excessive growth leads to a pinching off of nerve fibres.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307465
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