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  • Ultrastructure  (54)
  • Scanning electron microscopy  (15)
  • Lepidoptera
  • Springer  (69)
  • 1975-1979  (69)
  • 1975  (69)
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Verlag/Herausgeber
  • Springer  (69)
Erscheinungszeitraum
  • 1975-1979  (69)
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 102 (1975), S. 95-101 
    ISSN: 1432-072X
    Schlagwort(e): Coelastrum ; Chlorococcales ; Chlorophyta ; Ultrastructure ; Cell Wall ; Tubules ; Bristles ; Polymorphism ; Buoancy ; Taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Résumé La paroi cellulaire de Coelastrum est généralement composée de trois couches. La couche la plus externe a été plus particulièrement étudiée. Elle est composée de tubules dressées, et porte souvent de longues fibrilles dont le rôle serait de stabiliser l'algue dans son milieu. La morphologie de la paroi cellulaire peut se modifier en fonction du milieu.
    Notizen: Abstract The cell wall of Coelastrum is usually composed of three layers. The outermost layer was studied most extensively. It consists of erect tubules which often bear long bristles whose function may be to stabilize the algae in its environment. The cell wall can modify its morphology according to the environment.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 102 (1975), S. 129-137 
    ISSN: 1432-072X
    Schlagwort(e): Diazepam ; Benzodiazepines ; Scenedesmus ; Ultrastructure ; Photosynthesis ; Respiration ; Rubidium Uptake
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Effects of diazepam (Valium) on photosynthesis, chlorophyll/photosynthesis ratios, respiration, uptake of rubidium ions, and ultrastructure of Scenedesmus obliquus synchronized by a light-dark regimen of $$14:\overline {10}$$ hrs were determined. 80 and 160 μM diazepam, added to the nutrient medium at the start of the light-dark change (i.e., start of the cell cycle) gradually reduced rates of photosynthesis below the initial rates from the beginning of the experiment. Contents of chlorophyll, however, remained nearly unaffected. Consequently, the diazepam-treated cells had a higher chlorophyll/photosynthesis ratio—also with regard to respiration in order to calculate the gross photosynthesis. The occurrence of photorespiration cannot be assumed. The net influx or rubidium was slightly reduced by 100 μM diazepam 0.5 and 2.0 hrs after the start of the cell cycle and was strongly inhibited after 5 to 14 hrs. 80 and 160 μM diazepam caused separation of thylakoids, formation of giant mitochondria and enlargement of vacuoles. The results are discussed and it is finally suggested that diazepam acts on different membrane systems. Furthermore an ATP deficiency cannot be excluded.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 102 (1975), S. 155-161 
    ISSN: 1432-072X
    Schlagwort(e): Bacillus acidocaldarius ; Spores ; Germination ; Thermophile ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Spores of the thermophilic, acidophilic, Bacillus acidocaldarius were covered by a thick outer coat and a laminated inner coat (5.5 nm periodicity). Small membranous vesicles were present in the spore core and they disappeared as germination proceeded. After depolymerization of the cortex, and a 30% increase in spore diameter, a localized gap appeared in the laminated inner coat only. This inner coat gap was narrow and could be the whole length of the spore. The germ cell appeared to grow, or to be pushed towards the inner coat gap, at which stage the outer coat disappeared in the same localized area. As the vegetative cell grew out the spore coat fell away, with loose cortical material still attached to it. The young germ cell developed a large spherical electron dense inclusion body in the cytoplasm, at the same time as the ribosomal and nuclear areas became distinct.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 104 (1975), S. 271-277 
    ISSN: 1432-072X
    Schlagwort(e): Protoplasts ; Regeneration ; Wall Structure ; Pullularia ; Ultrastructure ; Membrane Splitting ; Aberrant Tubes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract During the process of degradation of the cell wall of the yeast form of Pullularia pullulans by the lytic system of Micromonospora chalcea samples were withdrawn at different times and observed under phase contrast and electron microscope. The progressive lysis of the walls reveals a fibrillar component inside the apparently amorphous wall. Freeze etched preparations of cells during the formation and regeneration of protoplasts show that the cellular membrane is split and this method allows the smooth external face of the membrane and other internal face covered by particles to be seen. The fact that the smooth face of the membrane is only visible during the preparation or the regeneration of protoplasts and very rarely when intact cells are fractured, suggests a strong adherence between cell wall and this external layer of the membrane. During the regeneration which takes place as in most of the yeasts and moulds, a special study of the extension of the cell wall is made and a possible mechanism for this extension of the regenerated cell wall is proposed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 106 (1975), S. 209-214 
    ISSN: 1432-072X
    Schlagwort(e): Cyanobacteria ; Colonial sheath ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The colonial sheath of Microcystis marginata has a definite structure as seen by light and electron microscopy, consisting of a relatively smooth inner surface and densely packed, long fibrils on the outer surface. The sheath initially forms around the single cell and expands by continual deposition of sheath material to accomodate the synchronously dividing cells of the colony.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 157 (1975), S. 457-465 
    ISSN: 1432-0878
    Schlagwort(e): Pecten oculi ; Pigeon ; Surface ; Function ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary A scanning electron microscopic study of the pecten reveals the rib-like character of the pectinal folds, the nature of their connections with the base and bridge of the pecten as well as the presence of interconnections between the bundles of superficial collagenous fibres. It has been suggested that the pecten may have a mechanical significance, namely protection of the retina from the excessive movements of the vitreous humour. The relationship between the superficial membrane of the folds which is continuous, the intercellular spaces and the process of diffussion has also been discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    ISSN: 1432-0878
    Schlagwort(e): Sympathetic ganglia ; Nerve growth factor ; Enzyme induction ; Ultrastructure ; Morphometry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Nerve cells of the superior cervical ganglion of young rats (20 g body weight) were investigated electron microscopically 6 h, 24 h, 48 h and 5 days after subcutaneous injection of nerve growth factor (10 μ/g body weight every 24 h). By means of a planimetric method with high accuracy significant changes of the Nissl substance and the Golgi apparatus could be demonstrated as early as 6 h after injection. Within the Nissl bodies both the density of bound ribosomes on the cisternae of the rough endoplasmic reticulum and the density of free ribosomes and polysomes decreased in a given field. This finding reflects a rearrangement of the Nissl substance and a spreading over larger areas of the cytoplasm, indicating an activation of the ribosomal system. The Golgi apparatus, in particular its outer part, increases in volume with time of nerve growth factor treatment. On the other hand, the total cell volume does not show significant changes before 48 h of nerve growth factor treatment. At this time an increase in the cytoplasmic volume can be seen, whereas the nuclear volume remains unchanged. The possibility of correlations of the present findings with data from biochemical studies done under similar experimental conditions is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 159 (1975), S. 73-80 
    ISSN: 1432-0878
    Schlagwort(e): Osteoblasts ; Collagen orientation ; Parietal bone ; Rat, Rhesus monkey ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Bone was removed from the calvaria of anaesthetized 70 g rats or freshly killed young monkeys and the fibrous periosteum dissected off the inner, formative surface under 0.15 M cacodylate buffer. The bone and undisturbed osteoblasts were fixed in 3% glutaraldehyde in the same buffer for 24 to 48 hours, critical point dried and coated with evaporated carbon and gold for scanning electron microscopy (SEM). Fields of osteoblasts were photographed and chosen cells dissected off the osteoid using a tungsten needle. The control of the dissection was made possible by the use of a system of real-time stereo TV-speed SEM. The fields were rephotographed and the orientations of the osteoblasts were compared with that of the underlying collagen fibres. 62% of all osteoblasts lay with their long axes within 15° of the collagen fibre orientation below and 80% within 30°. Montages of large areas of osteoblasts were also made, and then compared with ones of the same area after the cells had been stripped off on adhesive tape. In general, the orientation of the collagen tended to be the same as the cell that formed it. Collagen fibres below cells at the periphery of a domain sometimes had the orientation of the cells in the adjacent patch. It is not possible to determine whether the cells controlled the orientation of the collagen, or vice versa, from this experiment, but other SEM evidence suggests that the collagen orientation in hard tissue matrices depends on the freedom of cells to move with respect to the matrix surface.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 159 (1975), S. 233-243 
    ISSN: 1432-0878
    Schlagwort(e): Odontoblasts ; Predentine ; Dentine ; Calcification ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary A scanning electron microscopic technique was used to investigate the surface structure of dentinogenically active odontoblasts. Thin pieces of rat incisors were fixed, rapidly frozen, freezedried at -70° C and fractured to expose new surfaces prior to examination in the SEM. Differences in the appearance of odontoblastic cell surfaces were seen, with the most extensive ridge formations at the distal part of the sides of the odontoblasts. The predentine area displayed a spongy structure which contrasted to the compact appearance of dentine. Results are discussed in relation to previous studies at the light microscopic and transmission electron microscopic levels.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 159 (1975), S. 245-266 
    ISSN: 1432-0878
    Schlagwort(e): Neuromuscular junctions ; Rete synapticum ; Development ; Antheraea ; (Lepidoptera) ; Trophic action ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ultrastructure of neuromuscular connections on developing dorsolongitudinal flight muscles was studied in the moth Antheraea polyphemus, Undifferentiated membrane contacts between axon terminals and muscle-fiber anlagen are present in the diapause pupa. They persist during the period of nerve outgrowth, which probably provides a pathway of contact guidance. By the 4th day of adult development some of these contact areas have differentiated into structures similar to neuromuscular junctions although differentiation of muscle structure does not start earlier than the eighth day. Dense-cored vesicles are abundant in many axon terminals at the beginning of development. They later decrease in number quite rapidly. The significance of the above-mentioned early junctions, their possible mode of action and the role of the dense-cored vesicles are discussed. It is proposed that they exercise a stimulating (trophic) influence on the growth of the undifferentiated muscular tissue. The imaginai neuromuscular junctions are formed during the second half of adult development. Clusters of vesicles and electron-dense depositions along the inner face of the axolemma seem to initiate junction formation. Glial processes then grow between axoand sarcolemma and divide the large contact area into several small segments. Mutual invaginations and protrusions of the sarcolemma and the glial cell membrane subsequently form an extensive “rete synapticum.” Six days before eclosion the glial and sarcoplasmic parts of the rete synapticum are similar in size. Up to eclosion, all glial processes shrink and increase in electron density. Most of the observations are discussed also in relation to findings in vertebrates.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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