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  • 1
    Electronic Resource
    Electronic Resource
    Histological observations on lymphomyeloid organs of the Antarctic fish Trematomus bernacchii (Teleostei: Nototheniidae) (1997)
    Springer
    Polar biology 18 (1997), S. 358-362 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lymphomyeloid organs of the Antarctic fish Trematomus bernacchii were studied with the aim of analysing some morphological aspects related to adaptation to low environmental temperature. The thymus of T. bernacchii was flattened, incompletely lobated and scarcely regionalised. It was filled by lymphoid elements intermingled with stromal elements. The head kidney appeared highly vascularised and mainly lymphopoietic. The spleen appeared mainly erythropoietic, with scarcely developed areas of white pulp.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050200
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  • 2
    Electronic Resource
    Electronic Resource
    Spermatophore development and sperm ultrastructure in Craterostigmus tasmanianus (Chilopoda, Craterostigmomorpha) (1996)
    Springer
    Zoomorphology 116 (1996), S. 103-110 
    Details
    ISSN: 1432-234X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Spermatophore development and ultrastructure of the mature sperm of Craterostigmus tasmanianus were studied using light and electron microscopy. In C. tasmanianus, as in the Scolopendromorpha, the spermatophore develops within the vas deferens. The latter consists of three parts, each with a different morphology. The first may be involved in guiding the sperm to roll up into typical ring-like structures, while the other two, which show an evident secretory activity, secrete the acellular wall of the spermatophores. The ultrastructure of mature spermatozoa showed that a very close similarity exists between Craterostigmomorpha and Lithobiomorpha, especially regarding the organization of the connecting piece. Based on this similarity, we consider the Craterostigmomorpha together with the Scolopendromorpha, Geophilomorpha and Lithobiomorpha (=Pleurostigmophora) to be the sister group of the Scutigeromorpha.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004350050013
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Confocal scanning laser microscopy of the follicular epithelium in ovarioles of the stick insect Carausius morosus (1998)
    Springer
    Cell & tissue research 293 (1998), S. 551-561 
    Details
    ISSN: 1432-0878
    Keywords: Key words Follicular epithelium ; Insect ovarioles ; Confocal laser microscopy ; Carausius morosus (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Ovarian follicles of the stick insect Carausius morosus were analyzed by confocal laser microscopy and immunocytochemistry with a view to studying cell polarity in the follicular epithelium. Such probes as anti-α-tubulin antibodies and Rh-phalloidin were employed to establish how the follicle cell cytoskeleton changes during ovarian development. Data show that α-tubulin prevails over the basal end, while F-actin appears more abundant along the apical end of the follicle cells. This finding was further corroborated by immunogold cytochemistry, showing that label along the basal end is primarily associated with microtubules, while that along the apical end is due to follicle cell microvilli interdigitating with the oocyte plasma membrane. A monoclonal antibody specifically raised against a vitellin polypeptide was used to investigate the role the follicular epithelium might play in relation to vitellogenin (Vg) uptake by the oocyte. Data show that under these conditions label is restricted to the intercellular channels of the follicular epithelium, thus providing further support to the notion that Vg enters the oocyte through the extracellular pathway leading from the basement lamina to the oocyte surface. By contrast, the use of a monoclonal antibody raised against a fat-body-derived protein of 85 kDa that is specifically sulfated within the follicle cells provides evidence for the existence of an alternative way of gaining access to the oocyte surface, that is by transcytosis through the follicular cell epithelium. These findings confirm our earlier observations on stick insect ovarioles whereby polarization in the follicular epithelium is primarily addressed to sustain a transcytotic vesicular traffic between opposite poles of the follicle cell of Vg toward the oocyte surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051147
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  • 4
    Electronic Resource
    Electronic Resource
    The follicle cell-oocyte interaction in ovarian follicles of the stick insect Bacillus rossius (Rossi): (Insecta: Phasmatodea) (1985)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 185 (1985), S. 37-49 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Developing ovarian follicles of Bacillus rossius have been examined ultrastructurally in an attempt to understand how inception of vitel-logenesis is controlled. Early vitellogenic follicles are characterized by a thick cuboidal epithelium that is highly interlocked with the oocyte plasma membrane. Gap junctional contacts are present both at the follicle cell/oocyte interface and in between adjacent follicle cells. In addition, microvilli of follicle cells protrude deeply into the cortical ooplasm of these early vitellogenic oocytes. With the onset of vitellogenesis, wide intercellular spaces appear in the follicle cell epithelium and at the follicle cell/oocyte interface. Gap junctions become progressively reduced both on the follicle cell surface and on the oocyte plasma membrane. Microvilli from the two cell types no longer interlock.From a theoretical standpoint each of the two structural differentiations present at the follicle cell/oocyte interface - gap junctions and follicle cell microvilli - could potentially trigger inception of vitellogenesis. Gap junctions might permit the passage of a regulatory molecule, transferring from follicle cells to oocyte, which would control the assembly of coated pits on the oocyte plasma membrane. Alternatively cell interaction via microvilli might induce the appearance of coated pits, thus creating a membrane focus for vitellogenin receptors. Both possibilities are discussed in relation to current literature.
    Additional Material: 24 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051850103
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Oogenesis of the mayfly Habrophlebia eldae: Synthesis of vitelline and chorionic envelopes (1988)
    New York, NY : Wiley-Blackwell
    Gamete Research 21 (1988), S. 439-450 
    Details
    ISSN: 0148-7280
    Keywords: oocyte growth ; Ephemeroptera ; egg shell ; electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The ultrastructure of developing ovarian follicles inside the panoistic ovarioles of Habrophlebia eldae were examined to observe the events occurring during egg maturation up to the full formation of the chorionic envelopes. The early vitellogenic follicles are coupled by gap junctions and are extensively interlocked with the oocyte plasma membrane via microvilli. With the onset of vitellogenesis, coated pits and coated vesicles are precursors to yolk deposition and are visible at the follicle cell-oocyte interface. Postvitellogenic development entails the deposition of the egg envelopes. The vitelline envelope arises from the coalescence of rectangular plaques whose precursors are visible in Golgi complexes as heterogeneous electron-opaque granules. A chorionic pattern of ridges on the egg surface characterizes the shell of H. eldae. The fully developed chorion shows three distinct regions with differently organized patterns. A fine layer of fibrous material (a secretion of the follicle cells, Ephemeroptera devoid of accessory glands) adheres to the egg chorion and is probably involved in attachment to the substrate.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120210411
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    Paper (German National Licenses)
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