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'Electron Microscopy' in keywords Facet   Publication Year 1992  [X]
Facet   section ZfN Section C:Volume 047  [X]
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1Author    Ulrich SchraermeyerRequires cookie*
 Title    Evidence for a Pathway of Distal Screening Pigment Granules across the Basement Membrane of the Crayfish Photoreceptor  
 Abstract    The distal pigment cells o f Orconectes limosus contain two layers o f large electron lucent vacuoles that are separated by layers o f small right-angled platelets adjacent to the crystalline cones. The crystalline cones o f the dioptric apparatus o f this species have evaginations into the distal pigment cell cytoplasm. In photoreceptors o f Orconectes limosus and Procambarus clar-kii a dark pigment accumulation site was detected just distal to the basement membrane at the edges o f each retina. These pigment accumulations occurred independent o f the state o f light adaptation. Ultrastructurally the pigment granules at this accumulation site resemble distal screening pigment granules according to their size (up to 1.2 jim in diameter) and fibrous structure. Distal screening pigment granules were also found in tube-like cell processes or ex-tracellularly within and proximal to the retinal basement membrane, indicating pigment trans­ port to and across the basement membrane. Proximal to the basement membrane screening pigment granules were also observed disintegrated to a gravel-like electron dense material in widely branched cells. Evidence was found that an electron dense material, probably resulting from disintegrating screening pigment granules, was incorporated in the integument o f the eyestalk. Four hours after injection o f gold particles into the eye stalk distal to the retina they were detected inside and proximal to the retinal basement membrane. 
  Reference    Z. Naturforsch. 47c, 453 (1992); received June 13 1991/February 11 1992 
  Published    1992 
  Keywords    Electron Microscopy, Crayfish, Distal Screening Pigment Granules, Basement Membrane, Crystalline Cone 
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 TEI-XML for    default:Reihe_C/47/ZNC-1992-47c-0453.pdf 
 Identifier    ZNC-1992-47c-0453 
 Volume    47