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  • Compound eye  (5)
  • Symbiotes  (4)
  • Blood-brain barrier  (3)
  • Cell & Developmental Biology  (3)
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Keywords
  • 1
    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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  • 2
    Electronic Resource
    Electronic Resource
    The large pigment cell of the compound eye of the house fly Musca domestica (1976)
    Springer
    Cell & tissue research 170 (1976), S. 77-88 
    Details
    ISSN: 1432-0878
    Keywords: Compound eye ; House fly ; Large pigment cells ; Corneal pigment cells ; High voltage and conventional electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure and cellular associations of the large pigment cells (LPC's) of the compound eye of the house fly were studied with high voltage and conventional electron microscopy. Depending on the sector of the compound eye, the facets are either rectangular or hexagonal. The underside of each facet has indentations exactly aligned with those on top into which inserts an angulated sleeve of LPC's. Under the rectangular lens facet 6 or 8 small compact (in cross section) LPC's join four elongate LPC's. Clusters of compact cells alternate in this ring with elongate ones. Compact cells compress together and become quadrangular (in cross section) several microns below their insertion into the lens and form “building block” corners while elongate cells form “side rails” for the rectangular type of distal pseudocone enclosure. Beneath hexagonal facets all LPC's are rather elongate with out corner cells. In both facet types LPC's enclose the pseudocone for a longitudinal distance of 4 μm and then are displaced as bordering cells by a sleeve of two corneal pigment cells (CPC's), each of which encloses half of the proximal pseudocone. For the following 6 μm of longitudinal distance these concentric sleeves of CPC's and LPC's form a double layer around the pseudocone. At about 10 μm below lens base the two sleeves separate; LPC's become attenuated and extend cable-like to the basement membrane and CPC's enclose the proximal pseudocone, Semper cells and distal retinula. The junction between lens and LPC's has critical structural value in that (1) this is the sole anchorage to the lens by the lengthy remainder of the ommatidium, and (2) LPC's enclose the semiliquid pseudocone in the most distal portion of the pseudocone. In addition to vertical support, the LPC's send out numerous lateral processes that make structural contact among themselves, with the corneal pigment cells and the photoreceptor cells. The structural features of this array are discussed relative to possible physiological roles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220111
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  • 3
    Electronic Resource
    Electronic Resource
    Comparative ultrastructure and blood-brain barrier in diapause and nondiapause larvae of the European corn borer Ostrinia nubilalis (Hübner) (1975)
    Springer
    Cell & tissue research 162 (1975), S. 499-510 
    Details
    ISSN: 1432-0878
    Keywords: Blood-brain barrier ; Moth ; Diapause ; ATPase ; Peroxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural examination of diapause and nondiapause larval brains of the European corn borer disclosed anatomical differences that may be related to the insect's “blood-brain barrier.” The perineurial type I cells are quite closely appressed in the diapause brain, but thrown into extensive folds with large intercellular spaces in the nondiapause brain. The perineurial type II cells of diapause and nondiapause larvae are basically similar in general ultrastructure, and most likely form the basis for the “blood-brain barrier.” Horseradish peroxidase penetration studies indicated that the outer margin of the perineurial type II cells constitute the limits of infiltration into the brain. An enzymatic component of the “blood-brain barrier” is postulated in this insect. The localization of ATPase in the perineurial type II cells indicates that energy-requiring regulatory mechanisms may be localized here. Metabolic studies with isolated insect brains, coupled with recent evidence from mammalian systems, suggest that glial cells may be of importance in an enzymatic “blood-brain barrier.”
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209349
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  • 4
    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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  • 5
    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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  • 6
    Electronic Resource
    Electronic Resource
    Analog of vertebrate anionic sites in blood-brain interface of larval Drosophila (1994)
    Springer
    Cell & tissue research 277 (1994), S. 87-95 
    Details
    ISSN: 1432-0878
    Keywords: Blood-brain barrier ; Anionic sites ; Larvae ; Septate junctions ; CNS ; Glia ; Ultrastructure ; Drosophila melanogaster (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The blood-brain barrier ensures brain function in vertebrates and in some invertebrates by maintaining ionic integrity of the extraneuronal bathing fluid. Recent studies have demonstrated that anionic sites on the luminal surface of vascular endothelial cells collaborate with tight junctions to effect this barrier in vertebrates. We characterize these two analogous barrier factors for the first time on Drosophila larva by an electron-dense tracer and cationic gold labeling. Ionic lanthanum entered into but not through the extracellular channels between perineurial cells. Tracer is ultimately excluded from neurons in the ventral ganglion mainly by an extensive series of (pleated sheet) septate junctions between perineurial cells. Continuous junctions, a variant of the septate junction, were not as efficient as the pleated sheet variety in blocking tracer. An anionic domain now is demonstrated in Drosophila central nervous system through the use of cationic colloidal gold in LR White embedment. Anionic domains are specifically stationed in the neural lamella and not noted in the other cell levels of the blood-brain interface. It is proposed that in the central nervous system of the Drosophila larva the array of septate junctions between perineurial cells is the physical barrier, while the anionic domains in neural lamella are a “charge-selective barrier” for cations. All of these results are discussed relative to analogous characteristics of the vertebrate blood-brain barrier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00303084
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  • 7
    Electronic Resource
    Electronic Resource
    The distal ommatidium of the compound eye of the housefly (Musca domestica): A scanning electron microscope study (1975)
    Springer
    Cell & tissue research 159 (1975), S. 379-385 
    Details
    ISSN: 1432-0878
    Keywords: Compound eye ; Musca domestica ; Ommatidium ; Distal retinula ; Scanning electron microscopy ; Corneal lens ; Corneal pigment cell ; Pseudocone ; Semper cell ; Basement membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distal aspect of the housefly ommatidium was surveyed by the scanning electron microscope. Attention was directed to the somal eminence of the superior central cell and the lens to large pigment cell junction. The underside of each lens facet exhibits six hexagonally arranged incisures. Into each of these indentations are fitted several large pigment cells. This hexagonal indentation appears to be a tenacious anchorage. Two corneal pigment cells laterally encircle the pseudocone and at their proximal extension they enclose the Semper cells and neck of the retinula. The somal eminence of the superior central cell is about 10 μm from the base of the corneal pigment cell enclosure. Micrographs were used to construct a diagram of the ommatidium above the basement membrane. Suggestions are made as to the functional correlates of the observed ommatidial structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221784
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of antibiotics on intracellular symbiotes in the pea aphid, Acyrthosiphon pisum (1974)
    Springer
    Cell & tissue research 148 (1974), S. 287-300 
    Details
    ISSN: 1432-0878
    Keywords: Symbiotes ; Aphids ; Antibiotics ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of penicillin and chlortetracyline HCl on the fine structure of the intracellular symbiotes of the pea aphid were studied in an attempt to remove the symbiote population. High penicillin concentrations, 1% and 0.1%, caused symbiote breakdown but were toxic and/or repellent to the aphids; at 0.1% specific effects were observed on the symbiotes' cell walls. After the use of 0.01% penicillin in the aphid diet, the symbiotes had abnormal cell walls and were abnormally dilated; however, symbiote division and transmission from one aphid generation to the next seemed unaffected and the aphids appeared normal. Aphids fed 0.1% chlortetracycline failed to reproduce. After 7 days, their symbiotes were found to break down at a high rate but aphid mitochondria were also adversely affected at this stage. Following 0.002% chlortetracycline, the aphids produced aposymbiotic progeny with apparently normal mitochondrial populations; these larvae failed to develop.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224257
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  • 9
    Electronic Resource
    Electronic Resource
    Ultrastructure of pea aphid mycetocytes: Evidence for symbiote secretion (1975)
    Springer
    Cell & tissue research 159 (1975), S. 351-367 
    Details
    ISSN: 1432-0878
    Keywords: Symbiotes ; Aphids ; Vesicles ; Organelles ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A detailed investigation into the ultrastructure of the pea aphid mycetocytes and their contained symbiotes and organelles was carried out with the transmission electron microscope. The most striking observation was the presence of small vesicles in the space between the primary symbiote cell wall and membrane envelope (outer membrane space). The vesicles appear to form by a budding process at the outer cell wall layer. Subsequently, the vesicles, we suggest, may move out into the mycetocyte cytoplasm via a similar budding of the membrane envelope. The Golgi apparatus was found to be an important structural component of the primary mycetocyte; it is continuous with the rough endoplasmic reticulum and the latter, in turn, appears to be closely connected to the primary symbiote membrane envelope. This may be of functional significance. A number of other organelles not previously described in mycetocytes were found, including transparent vacuoles, granular bodies, multivesicular bodies and microfilaments. The chemical composition of the various vesicles and organelles is unknown at present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221782
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  • 10
    Electronic Resource
    Electronic Resource
    Ultrastructure of capitate projections in the optic neuropil of Diptera (1986)
    Springer
    Cell & tissue research 246 (1986), S. 481-486 
    Details
    ISSN: 1432-0878
    Keywords: Glia ; Photoreceptors ; Compound eye ; Lamina ganglionaris ; Capitate projections ; Diptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Photoreceptor axons in the first optic neuropil of the dipteran flies Musca domestica and Drosophila melanogaster were examined with electron microscopy. The objective was to determine ultrastructure, persistence and glial source of the capitate projections found within these neurons. Capitate projections are simple or compound processes of epithelial glial cells which profusely insert into form-fitting folds of axon terminals of the peripheral retinular cells (R1–6) in the synaptic plexus portion of the first optic neuropil. These neuro-glial junctions may be simple indentations, have a head with a single stalk, or possess a single, circular stalk from which 3 or 4 bulbous (glial) heads are elaborated. Using serial thick sections of Drosophila neuropil for HVEM we were able to observe that the stalks connecting nearly all capitate projections led directly to a glial cell. Thus no disembodied heads were found suspended in axoplasm. Capitate projections appeared to be persistent structures, present in young as well as senescent adults. No evolution of form was found; thus 3 distinct expressions of these glial processes (without transitional forms) are present. From freeze-fracture replicas and serial HVEM sections it was determined that there were approximately 3 capitate projections per μm2 in Drosophila and Musca, respectively. About 800 capitate projections exist per Musca axon terminal or about 5 times the number of chemical synapses. Cp's were slightly larger in Drosophila than in Musca, although the Musca retinular axon has twice the diameter and length of that of the fruit fly. The evidence was reviewed in light of the likely supportive function of capitate projections on the R1–6 terminals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215187
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