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  • 1985-1989  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Utrastructural study of oogenesis and oocytic degeneration in Pecten maximus from the Bay of St. Brieuc (1989)
    Springer
    Marine biology 103 (1989), S. 339-348 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An ultrastructural study of oocytic development enabled the identification of changes occurring during oogenesis in Pecten maximus collected from the Bay of St. Brieuc, France, in 1987. “Auxiliary cells”, closely associated with developing oocytes were observed. Each oocyte seems to be associated with only one secretory cell, which is characterised by an abundant rough endoplasmic reticulum at the onset of vitellogenesis. Contact between this cell and a developing oocyte is maintained by a desmosome-like junction which can be observed when the vitelline coat is formed. These “auxiliary cells” seem to play a trophic role in vitellogenesis, and may be involved in the formation of the vitelline coat of the oocytes. Oocytic degeneration is discussed in detail; in this species, it is a continuous phenomenon of varying intensity throughout the year. The ultrastructural changes resulting in lysis of the oocyte are described, and the evolution of atretic oocytes is examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397268
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Chemoautotrophic symbionts and translocation of fixed carbon from bacteria to host tissues in the littoral bivalve Loripes lucinalis (Lucinidae) (1989)
    Springer
    Marine biology 101 (1989), S. 305-312 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Specimens of Loripes lucinalis (Lucinidae) living in reducing sediments were collected near a sewage outfall at low tide on the Moulin Blanc beach, Brest, France, from January to March 1987. Electron microscope studies revealed numerous Gram-negative-type bacteria in the gill cells. Ribulosebiphosphate carboxylase, a diagnostic enzyme of the Calvin-Benson cycle of CO2-fixation was measured only in the gill extracts. Various tissues of L. lucinalis were examined for activity of APS reductase, (EC 1.8.99.2), ATP sulphurylase (EC 2.7.7.4) and rhodanese (EC 2.8.1.1), enzymes involved in sulphide oxidation. APS reductase was only found in symbiont-containing tissues, i.e., gills. These enzymatic studies characterise the symbionts as chemoautotrophic sulphide-oxidizing bacteria. Histoautoradiography demonstrated that part of the carbon dioxide fixed by symbiotic bacteria in the gills is translocated to symbiont-free tissues of the bivalve. The ultrastructure of the gill is detailed and a nomenclature based on established and new terminology is proposed to describe the various cellular types comprising the gill filament.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00428126
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Ultrastructure of the gill of the hydrothermal-vent mytilid Bathymodiolus sp. (1986)
    Springer
    Marine biology 92 (1986), S. 65-72 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Specimens of Bathymodiolus sp. were collected at 2 620 m depth during the “Biocyarise” Cruise (12°58′80″N; 13°56′60″W) in March 1984, and samples of the gill were fixed for ultrastructural observations. The gill of this hydrothermal-vent mytilid constitutes the main organ in the nutritional processes. The lamellae display abundant ciliation, normally comprised of frontal cilia, compound latero-frontal cirri and lateral cilia. At the ventral margin of each demi-branch, a longitudinal, ciliated, feeding groove is present. the lamellae are composed of numerous homorhabdic filaments connected by tufts of cilia. Each filament is made of a thin wall overlying a central lumen containing amoebocytes. Ultrastructural observations revealed the filament wall to be composed of four types of cells: (1) The ciliated cells of the frontal, latero-frontal and lateral ciliation, characterized by an abundance of mitochondria. (2) Mucous cells present to some degree among the ciliated cells, but more abundant on the distal edge and containing dense droplets of mucus. (3) Cells colonized at their apical pole by numerous bacteria enclosed in membrane-delimited clear spaces and composing the major part of the filament wall. (4) Thin ciliated cells separating the bacterial cells and characterised by a dense fringe of microvilli at their apical pole. The lumen of the filament contains amoebocytes of different morphological aspects which seem to accumulate electron-dense granules, possibly related to detoxification processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392747
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    New observations of the gills of Placopecten magellanicus (Mollusca: Bivalvia), and implications for nutrition (1988)
    Springer
    Marine biology 98 (1988), S. 61-70 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The organization, general anatomy, and surface microanatomy of all regions of the gills of a representive bivalve mollusc, Placopecten magellanicus Gmelin, were studied using stereo-microscopic, histological, and scanning electron microscopic techniques. Individuals were collected in May and November 1985 from Chamcook Bay, New Brunswick, Canada. In addition to correcting earlier accounts of this structure, a number of new observations are reported. The orientation of the ciliated spurs appears to be responsible for the sinusoidal arrangement of the gill filaments. Micrographs showing the structure of the dorsal respiratory expansion are presented. The entire abfrontal surface of the principal filament, including the dorsal respiratory expansion, is densely ciliated and mucosecretory. These characteristics may aid in the establishment of a respiratory current and in the prevention of gill damage during escape responses. All nonciliated regions of the gill filaments are covered with microvilli, thus greatly increasing the surface area of the gill. The feeding mechanism is discussed in relation to the dorsal and ventral ciliated tracts. Symbiotic ciliate protozoans are constantly dislodged from the gill filaments and transported via the ventral mucus string to the buccal region. The nutritional implications of these observations are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392659
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    New observations of the gills of Placopecten magellanicus (Mollusca: Bivalvia), and implications for nutrition (1988)
    Springer
    Marine biology 98 (1988), S. 229-237 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The internal anatomy and microanatomy of the gill of Placopecten magellanicus Gmelin collected in May and November 1985 from Chamcook Bay, New Brunswick, Canada, was studied using thin-section light microscopy and transmission electron microscopy. Most of the spurs show no evidence of organic union, and hence do not participate in vascular exchange. However, the dorsal bend shows both ciliary and organic interfilamentar union. The internal structure and the hemocytes of the dorsal respiratory expansion are presented. The epithelium consists of three distinct cell types, bounded by apical microvilli. All regions of the gill contain an epithelial basal membrane, which is greatly convoluted in the interconnecting vessels of the dorsal respiratory expansion. The significance of these observations is discussed in relation to possible roles in respiration, transmembrane transport and nutrition. The apical surface of all ciliated cells is covered with an acellular matrix composed of clear spherical vesicles, which may serve a mechanical function for which mucus would be unsuited. The significance of the abundance of mucocytes on the abfrontal surface of the principal filaments is discussed in terms of the escape response of pectinid bivalves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391199
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Isthmus and ligament interrelationships: A computerized analysis of the spatial relationships of the hinge structures in unionid mussels (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 217 (1987), S. 8-15 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A study of the isthmus and ligament in unionid mussels was undertaken employing methods specifically designed to preserve the in vivo relationships of these interrelated structures. Serial sections of the hard and soft tissues were used for two-dimensional analysis. From these, a tridimensional computerized reconstruction was developed. Special dissections of the undisturbed isthmus were also utilized. By using such methodologies, a new description of the ligament has been developed employing such terminology as the foliated ligament and the posterior folding laminae. Similarly, for the isthmus, an anterior lyre, a pallial crest, a pallial peduncle, and a posterior lyre are described. Such entities are both morphologically and physiologically related to the shell and ligament.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092170103
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    Paper (German National Licenses)
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