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  • 2000-2004  (1)
  • 1985-1989  (4)
  • 1
    Electronic Resource
    Electronic Resource
    The architecture of the canal systems of Petrosia ficiformis and Chondrosia reniformis studied by corrosion casts (Porifera, Demospongiae) (1988)
    Springer
    Zoomorphology 108 (1988), S. 161-166 
    Details
    ISSN: 1432-234X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The three-dimensional organization of the canal system in two sponge species, Petrosia ficiformis and Chondrosia reniformis, was studied using corrosion casts. Casts were made of live animals, in situ, and canal replicas were analzyed by scanning electron microscopy (SEM). In P. ficiformis the incurrent system consists of a superficial canal network giving rise to large radial canals, which ramify and anastomosize forming an internal web. Excurrent canals are arranged into modular ramified systems radiating from atrial cavities opening to the exterior. Main excurrent canals run at various depths within the sponge, even through the superficial incurrent network. Both incurrent and excurrent canal replicas show smooth, blind-ending capillaries. Some large incurrent canals merge with excurrent ones, thus bypassing choanocyte chambers. In C. reniformis there is a cortical collagen layer crossed by three-like incurrent canals, the “twigs” of which communicate with groups of inhalant pores. The stems of tree-like canals penetrate into the sponge medulla where they ramify and anastomosize to form a web. Main excurrent canals arise from large cloacal ducts leading to the oscular openings. They give rise to a sequence of branches intersecting the incurrent web. Both incurrent and excurrent canals have sharp, blind-ending capillaries. Morphometric data functions show that diameter scaling in canal branches is exponential in Petrosia and linear in Chondrosia. Structural differences and homologies between the two species are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00363932
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  • 2
    Electronic Resource
    Electronic Resource
    The locomotion of dissociated sponge cells: A cell-by-cell, time-lapse film analysis (1985)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 5 (1985), S. 463-473 
    Details
    ISSN: 0886-1544
    Keywords: sponge dissociates ; cell migration ; time-lapse analysis ; cell aggregation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The production of both lamellipodia and peculiar thin protuberances (scleropodia) characterizes the preaggregative motility of cells after dissociation of the sponge Clathrina.The locomotory paths taken by cells before aggregation were recorded by time-lapse microcinematography. Changes of direction in successive 50-s time intervals and 50-s mean velocities of each cell were both taken into account as statistical variables. Their distributions give probability density curves that seem to fit bilateral exponential functions. The analysis of the angles of turn indicates a tendency for the cells to persist in their direction of motion and to make counter-clockwise turns. Implications of such in vitro cellular behaviors in aggregative and in vivo processes are suggested.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970050604
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  • 3
    Electronic Resource
    Electronic Resource
    The vacuolar cells of Oscarella lobularis (Porifera, Demospongiae): Ulatrastructural organization, origin, and function (1986)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 188 (1986), S. 29-37 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This work is concerned with the ultrastructural organization and some histochemical features of the vacuolar cells of the demosponge Oscarella lobularis. Vacuolar cells are characterized by large clear vacuoles containing an aqueous fluid. They are commonly found in the mesohyl of this sponge and tend to constitute a sort of parenchyma in the choanosome. Mobile cells of the mesohyl appear to differetiate into vacuolar cells through the progressive formation of wide cytoplasmic lacunae. We have identified four types of cells showing progressive transformation toward the vacuolar cell type. Precursors (types 1-4) of the vacuolar cells probably derive from endopinacocytes, since they share several histochemical and ultrastructural characteristics with them. Our data support the notion that vacuolar cells are involved in the synthesis of collagen, act as a mechanical support of the sponge body, and are eventually extruded from the sponge through the canals of the aquiferous system.
    Additional Material: 24 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051880104
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  • 4
    Electronic Resource
    Electronic Resource
    Ultrastructural study of the mature egg of Tethya citrina sarà and melone (porifera, demospongiae) (1987)
    New York, NY : Wiley-Blackwell
    Gamete Research 16 (1987), S. 259-265 
    Details
    ISSN: 0148-7280
    Keywords: reproduction ; oogenesis ; yolk ; sponges ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Tethya citrina is an oviparous demosponge in which eggs are distributed in clumps within the choanosome. The cytoplasm of the mature egg presents a peripheral cortex consisting of a slightly granular layer sandwiched between two densely granular, vesiculated ones. The cortex probably has a specialized, trophic function. Mesohyl bacteria are phagocyted at the egg surface, included in vacuoles, and transferred across the cortical sheath toward the inner cytoplasm. The region of the egg extending between the cortex and the nucleus shows a lacunary system mostly developed beneath the cortical envelope. The noncortical cytoplasm also contains lipid droplets, dense rodlike bodies, and phagosomelike granules. Most of the latter are probably autophagosomes, forming lacunae and supporting autosynthetic vitellogenesis. Rodlike inclusions are probably proteinaceous; they likely originate within the phagosomes and represent the actual yolk material.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120160308
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  • 5
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    Occurrence of Cu-ATPase in Dictyostelium: Possible Role in Resistance to Copper (2002)
    Elsevier
    Details
    Publication Date: 2002-03-01
    Print ISSN: 0006-291X
    Electronic ISSN: 1090-2104
    Topics: Biology , Chemistry and Pharmacology , Physics
    Published by Elsevier
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