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  • 1
    Electronic Resource
    Electronic Resource
    Crosslinking of theDrosophila chorion involves a peroxidase (1980)
    Springer
    Development genes and evolution 189 (1980), S. 187-196 
    Details
    ISSN: 1432-041X
    Keywords: Eggshell ; Chorion ; Peroxidase ; Crosslinking ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary TheDrosophila chorion contains an endogenous peroxidase activity which remains inactive until late stage 14 when it catalyzes the crosslinking of the chorionic proteins. Using explanted follicles developing in vitro, premature, but otherwise normal crosslinking can be induced with hydrogen peroxide and normal crosslinking can be prevented with peroxidase inhibitors. Inhibition or premature activation of the shell peroxidase allows characterization of chorionic filament specific proteins and establishes new criteria for the identification of eggshell components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00868677
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  • 2
    Electronic Resource
    Electronic Resource
    In vitro development of theDrosophila chorion in a chemically defined organ culture medium (1979)
    Springer
    Development genes and evolution 186 (1979), S. 351-362 
    Details
    ISSN: 1432-041X
    Keywords: Eggshell ; Chorion ; In vitro development ; Drosophila ; Tissue culture media
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary TheDrosophila chorion is produced normally in isolated follicles in Robb's chemically defined culture medium. The complex architecture of the shell developed in vitro from follicles as young as early stage 10 is completely normal morphologically. In addition, the time required for in vitro development closely approximates that observed for in vivo development. Comparisons of insect culture media developed by Robb, Grace, Schneider, and Echalier show large variations in their ability to supportDrosophila chorion development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848458
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The eggshell of hawaiianDrosophila: structural and biochemical studies inD. grimshawi and comparison toD. melanogaster (1983)
    Springer
    Development genes and evolution 192 (1983), S. 303-316 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila grimshawi, Diptera ; Eggshell structure ; Eggshell proteins ; Cell subpopulations ; Eggshell physiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The eggshell of the Hawaiian speciesDrosophila grimshawi was analyzed in terms of its structure and biochemical composition. It is generally similar toD. melanogaster in radial structure except that the inner endochorion is relatively compact and the outer endochorion is thick (1.9 μm) and traversed by numerous 50-nm-wide aeropyles (not present inD. melanogaster). Regionally the eggshell consists of the various specialized regions, which are: the holey posterior pole; the dorsal ridge; the operculum with very tall imprint borders; the collar with discontinuous outer endochorion; the micropyle with an external eccentric hole and an internal eccentric paracrystalline region; and the four very long respiratory appendages which exhibit tightly covered surface features for underwater plastron respiration. On the basis of the above structural data we suggest that the entireD. grimshawi eggshell (various layers and specialized regions) is the product of at least eight follicle cell subpopulations. In addition, in vitro culturing with3H-proline indicates that the eggshell is made according to a strict developmental program (analogous toD. melanogaster) and consists of several proteins ranging in molecular weight from 14,000 to 37,000 daltons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848810
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  • 4
    Electronic Resource
    Electronic Resource
    Ultrastructural features and formation of the micropylar apparatus in the cherry fly Rhagoletis cerasi (1991)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 208 (1991), S. 205-214 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The micropylar apparatus (MA) in Rhagoletis cerasi (Diptera, Tephritidae) is located at the anterior pole of the egg and consists of two parts: an outer chorion and an inner vitelline membrane. Sperm entry takes place through the micropylar canal, 2.0-2.5 μm in diameter, which penetrates the micropylar endochorion and terminates in the thick vitelline membrane, thus forming the “pocket.” The pore of the micropylar canal, i.e., the micropyle, is covered by the exochorionic tuft.The formation of the MA is accomplished by 40 micropylar cells during oogenesis. These cells secrete the successive eggshell layers: the vitelline membrane, the wax layer, the innermost chorionic layer, the micropylar endochorion, and the exochorion. Two among 40 micropylar cells differentiate and form two tightly connected projections. The latter contain a bundle of parallel microtubules and participate in the formation of the micropylar canal and the pocket. At the tip of the projections there are two thin extensions full of microfilaments. In late developmental stages the two projections and the extensions degenerate and leave the canal and the pocket behind. We also discuss the structural features of the MA in relation to its physiology among Diptera.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052080206
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  • 5
    Electronic Resource
    Electronic Resource
    Structure and morphogenesis of the eggshell and micropylar apparatus in the olive fly, Dacus oleae (Diptera: Tephritidae) (1991)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 209 (1991), S. 39-52 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The egg of the olive fly, Dacus oleae (Diptera, Tephritidae), is laid inside olives and the larva eventually destroys the fruit. The oocyte is surrounded by several distinct layers which are produced during choriogenesis. The chorion covering the main body of the egg outside of the vitelline membrane includes a “wax” layer, an innermost chorionic layer, an endochorion consisting of inner and outer layers separated by pillars and cavities similar to their counterparts in Drosophila melanogaster, as well as inner and outer exochorionic layers. The anterior pole is shaped like an inverted cup, which is chiefly hollow around its base and has very large openings communicating with the environment. Holes through the surface of the endochorion result from deposition of endochorionic substance around follicular cell microvilli. An opening at the apex of the cup provides an entrance for sperm entering the micropylar canal, which traverses the endochorion and continues into a “pocket” in a thickened vitelline protrusion. The micropylar canal is formed by deposition of endochorion and vitelline membrane around an elongated pair of follicular cell extensions. These extensions later degenerate and leave an empty canal about 5 μm in diameter and the narrower pocket about 1 μm in diameter. Respiration is thought to be facilitated by openings at the base of the anterior pole as well as by openings through the “plastron” around the main body of the shell.
    Additional Material: 36 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052090105
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