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  • 1975-1979  (2)
  • 1970-1974  (3)
  • Ommatidia  (3)
  • Cholesterol  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Scanning electron microscopy of the insect compound eye (1972)
    Springer
    Cell & tissue research 126 (1972), S. 437-445 
    Details
    ISSN: 1432-0878
    Keywords: Eye ; Sarcophaga bullata ; Ommatidia ; Lamina ganglionaris ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary External and internal surfaces of the compound eye of the flesh fly, Sarcophaga bullata, were examined with a scanning electron microscope. A low patterned corneal nippleridge array and sparse setiform interfacetal hairs were observed on the corneal lens surface. Particular cleavage planes revealed outlines of the Semper Cells, their nuclei and distal terminations of photoreceptor cells. The latter, with their axonal processes, were visualized and described. These axons were noted traversing the external chiasma and entering the lamina ganglionaris where suggestions of synaptic contact were pointed out. The present descriptions were correlated with those taken from literature of the transmission electron microscope.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00306904
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Surface fine structure of the eye of the housefly (Musca domestica): Ommatidia and lamina ganglionaris (1974)
    Springer
    Cell & tissue research 149 (1974), S. 21-41 
    Details
    ISSN: 1432-0878
    Keywords: Compound eye ; Musca domestica ; Ommatidia ; Optic cartridge ; Basement membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The compound eye of the housefly, from lens to first optic neuropile (lamina ganglionaris) was examined with a scanning electron microscope. Key findings are as follows: The pseudocone cavity is enclosed by six corneal pigment cells. The nuclei of the six cells are firmly anchored to the underside of the lens and portions remain after lens delamination from the pseudocone cavity. An eccentrically-positioned, short photoreceptor cell was observed near the region where the inferior central cell initiates its rhabdom. This eminence may represent that cell's soma. The basement membrane is revealed as a two-tiered, fibrous layer with ovoid fenestrations. Each opening is sealed with a diaphragm perforated by eight retinular axons and a trachea. Conjoined distal surfaces of the satellite glial cells form a membrane-like barrier immediately underlying the basement membrane. Monopolar somata from the lamina are covered with glial cells which possibly make more intimate contact with the somata through miniscule projections. Optic cartridges with monopolar interneurons were noted. Spherical to slightly biconcave processes of these interneurons contact retinular axons. Very fine (1000 Å) filaments interweave among and contact lateral processes. Further implications are discussed as they relate to observed structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209048
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    In vivo sterol biosynthesis by pea aphid symbiotes as determined by digitonin and electron microscopic autoradiography (1977)
    Springer
    Cell & tissue research 176 (1977), S. 179-190 
    Details
    ISSN: 1432-0878
    Keywords: Cholesterol ; Symbiotes ; Aphids ; Digitonin ; Autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pea aphid primary symbiotes have previously been shown to synthesize cholesterol in vitro. Two electron microscopic techniques were used here to determine whether the symbiotes also synthesize cholesterol in vivo and whether this cholesterol is made available to the aphid. We also inquired into a possible role of secondary symbiotes in cholesterol biosynthesis. Treatment of aphids with digitonin resulted in significant alteration of ultrastructural sites in primary and secondary symbiote membranes. We concluded that these sites are areas of high cholesterol concentration in the symbiotes. Electron microscopic autoradiography with 3H-mevalonate precursor indicated that both primary and secondary symbiotes synthesize cholesterol; in both cases, the majority of grains were associated with the symbiote membranes. While the frequency of grains on the symbiotes remained constant, irrespective of incubation time in labelled media, the frequency of grains over surrounding tissues increased exponentially as the time of incubation was increased from 30 min to 8 h, indicating that symbiote cholesterol is transported to other tissues. High voltage electron microscopic autoradiography permitted thick section autoradiography, reducing the time of emulsion exposure from 54 days (thin section) to 12 days (0.5 μm sections).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229461
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of dietary cholesterol on the pattern of osmium deposition in the symbiote-containing cells of the pea aphid (1977)
    Springer
    Cell & tissue research 176 (1977), S. 191-203 
    Details
    ISSN: 1432-0878
    Keywords: OsO4 ; Cholesterol ; Symbiotes ; Aphids ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pea aphids left for 48 h in unbuffered osmium tetroxide show heavy staining of many organelles in the symbiote-containing cells (mycetocytes and sheath), embryos and oenocytes very similar to that characteristic of mammalian sterol-synthesizing cells. However, the staining of the pea-aphid cells is, to a large extent, dependent on the presence of cholesterol benzoate, or free cholesterol, in the aphid's diet. In aphids cultured in vitro with 3H mevalonate in the presence of added cholesterol, the incorporation of label into the cholesterol and lanosterol fractions is significantly reduced. If the dietary cholesterol effects a similar inhibition in vivo, the cholesterol-dependent osmium staining could be due to precursors(s) of cholesterol accumulating in the intracellular sites described. There is also osmium staining of large (normally electron-transparent) vacuoles in mycetocytes, gut and fat body, irrespective of dietary cholesterol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229462
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Scanning electron microscopy of the insect compound eye (1972)
    Springer
    Cell & tissue research 126 (1972), S. 446-453 
    Details
    ISSN: 1432-0878
    Keywords: Eye ; Manduca sexta ; Ommatidia ; Retinula ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The superposition eye of the sphingid moth, Manduca sexta was explored by means of the scanning electron microscope (SEM). Specifically examined were the corneal nipple array, corneal lens, crystalline cones and tracts, photoreceptor cells and their axons. Descriptions of the external ultrastructure of the components were correlated, where possible with previously published accounts of internal ultrastructure as obtained from TEM studies. A key finding was the demonstration of the axial rotation of the eccentrically situated retinular cell, its externally noted prominence and the arrangement of the other photoreceptor cells composing the retinula. Because of the interest in superposition eye theory, the functional significance of various preretinular optic components was reviewed where it specifically related to Manduca.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00306905
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    Paper (German National Licenses)
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