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  • Articles  (2)
  • Cataglyphis bicolor, Apis mellifera, Musca domestica (Insecta) Tracheal system, insects  (1)
  • Melolontha melolontha (Insecta)  (1)
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  • Articles  (2)
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  • 1
    ISSN: 1432-0878
    Keywords: Compound eye ; Cornea ; Photoreceptor cells ; Polarized light detection ; Melolontha melolontha (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The superposition eye of the cockchafer, Melolontha melolontha, exhibits the typical features of many nocturnal and crepuscular scarabaeid beetles: the dioptric apparatus of each ommatidium consists of a thick corneal lens with a strong inner convexity attached to a crystalline cone, that is surrounded by two primary and 9–11 secondary pigment cells. The clear zone contains the unpigmented extensions of the secondary pigment cells, which surround the cell bodies of seven retinula (receptor) cells per ommatidium and a retinular tract formed by them. The seven-lobed fused rhabdoms are composed by the rhabdomeres of the receptor cells 1–7. The rhabdoms are optically separated from each other by a tracheal sheath around the retinulae. The orientation of the microvilli diverges in a fan-like fashion within each rhabdomere. The proximally situated retinula cell 8 does not form a rhabdomere. This standard form of ommatidium stands in contrast to another type of ommatidium found in the dorsal rim area of the eye. The dorsal rim ommatidia are characterized by the following anatomical specializations: (1) The corneal lenses are not clear but contain light-scattering, bubble-like inclusions. (2) The rhabdom length is increased approximately by a factor of two. (3) The rhabdoms have unlobed shapes. (4) Within each rhabdomere the microvilli are parallel to each other. The microvilli of receptor 1 are oriented 90° to those of receptors 2–7. (5) The tracheal sheaths around the retinulae are missing. These findings indicate that the photoreceptors of the dorsal rim area are strongly polarization sensitive and have large visual fields. In the dorsal rim ommatidia of other insects, functionally similar anatomical specializations have been found. In these species, the dorsal rim area of the eye was demonstrated to be the eye region that is responsible for the detection of polarized light. We suggest that the dorsal rim area of the cockchafer eye subserves the same function and that the beetles use the polarization pattern of the sky for orientation during their migrations.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 256 (1989), S. 1-6 
    ISSN: 1432-0878
    Keywords: Corrosion casts ; Tracheal system ; Respiration ; Scanning electron microscopy ; Insecta ; Cataglyphis bicolor, Apis mellifera, Musca domestica (Insecta) Tracheal system, insects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The tracheal systems of five insect species (two species of ants, worker bee, housefly and the cabbage butterfly) have been studied by scanning electron microscopy of corrosion casts. This technique, which is commonly used for the investigation of vertebrate vasculature, is adapted to demonstrate the ultrastructure of the insect respiratory organ. The problem of filling a “blind ending system” was solved by injecting the resin Mercox into the evacuated tracheae through a thoracal spiracle. After polymerization of the resin, the tissue was digested enzymatically and chemically. The three-dimensional structure of the tracheal system was investigated by scanning electron microscopy. The technique used here displays for the first time the complex morphology of the entire tracheal system in fine detail, especially the structure of spiracles, airsacs, tracheae and tracheoles. Smooth-walled terminal tracheoles show up in flight muscles. The finest tracheoles that could be identified have diameters of approximately 70 nm. This approaches the finest tracheoles portrayed by transmission electron micrographs.
    Type of Medium: Electronic Resource
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