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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 98 (1992), S. 289-298 
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A procedure is described in which large early spermatogonia were isolated from carp testes and purified from an initial 4–5% recovery up to 60–70% using equilibrium density centrifugation on a continuous Percoll gradient. Mice were immunized with the spermatogonia via the intrasplenic route. Six hybridoma cultures, producing monoclonal antibodies (MAbs) reacting selectively with germ cells, were selected and further analysed. Reactivity with five of these MAbs was observed on primordial germ cells (PGCs) in the developing indifferent gonads at the onset of proliferation, i.e. the age of 7 weeks. One MAb, encoded WCG 6, appeared to define a new surface marker on PGCs being gradually expressed on the surface membrane between the age of 2 and 4 weeks, concomitantly with an increase in size of these mitotically silent cells. The reactivity of germ cells with five of the MAbs disappeared completely (WCG 7, 12, 15, 21) or nearly completely (WCG 6) during spermatogenesis, providing a striking difference from patterns obtained with MAbs raised previously against carp spermatozoa. Differences between male and female germ cells were not observed with the WCG-MAbs during gonad development, indicating that a common set of surface antigens is shared between germ cells of both sexes up to and including spermatogonia and oogonia.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary During development of juvenile and young adult carp (Cyprinus carpio, L., Teleostei) three differentiation stages were distinguished in the testis: the prespermatogenic, the early spermatogenic and the advanced spermatogenic testis. Carp testis tissue of these stages was dissociated by enzymatic digestion and viable testis cells with well preserved morphological features were obtained. The surface location and stage-specificity of differentiation antigens on these germ cells was investigated using monoclonal antibodies (MAbs) raised against carp spermatozoa. Binding of MAbs to cells was visualized with immunofluorescence as well as in the immunogold staining assay. Both methods revealed that antigenic determinants defined by seven MAbs were located on the outer surface of testis cells. Four MAbs, i.e. WCS 3, 17, 28 and 29, reacted with germ cells from both pre-spermatogenic testes (WCS 28 weakly) and spermatogenic testes. The antigenic determinants defined by three other MAbs, i.e. WCS 7, 11 and 12, appeared only after the onset of spermatogenesis. In the immunogold staining assay a post-fixation and nuclear staining procedure was developed which allowed identification of isolated germ cells, revealing clearly, for all seven MAbs, that the determinants were expressed on germ cells but not on somatic cells and, for WCS 7, 11 and 12 only, that the determinants first appeared on small spermatogonia prior to meiosis. A survey of the immunogold assay on the binding of the seven MAbs with isolated germ cells from ovaries, is included.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 236 (1984), S. 99-105 
    ISSN: 1432-0878
    Keywords: Monoclonal antibodies ; Spermatozoa ; Surface antigens ; Reproductive organs ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Eleven monoclonal antibodies that recognize membrane determinants on spermatozoa of the carp Cyprinus carpio L. have been produced. Indirect immunofluorescence revealed that these determinants are uniformly distributed on the surface of head and midpiece. Most of them are also present on the outer membrane of precursor sperm cells. Although none of the monoclonal antibodies reacted with carp somatic tissue, five monoclonal antibodies were positive for surface membrane determinants of oogonia and early prophase oocytes in carp ovary. Preliminary analysis of the testis and ovary of three other species of fish showed that some carp determinants are shared with germ cells from Barbus conchonius, Clarias lazera, or Salmo gairdneri.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 242 (1985), S. 75-81 
    ISSN: 1432-0878
    Keywords: Blood-gonad barrier ; Monoclonal antibodies ; Horseradish peroxidase ; Immunohistochemistry ; Teleost fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Physiological compartmentation in carp (Cyprinus carpio L.) gonads was investigated after intracardial injection of horseradish peroxidase (HRP) and two mouse anti-carp-sperm monoclonal antibodies. Immunohistochemistry revealed that a physiological barrier exists in carp testis for HRP and mouse IgG monoclonal antibody around the central lumina of the tubules in which the spermatozoa are located, but not around the cysts containing the precursor germ cells. The results with HRP were confirmed by electron microscopy. Mouse IgM monoclonal antibody did not penetrate the spermatogenic cysts. Probably because of its large size, it was almost exclusively located inside blood capillaries and only sparsely in the interstitial tissue. In the ovary, HRP was regularly distributed in the gonadal tissue, whereas the IgG antibody was predominantly localised on oogonia and early prophase oocytes. The results indicate that in contrast with the testis, no barrier around germ cells exists in the carp ovary.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0878
    Keywords: Primordial germ cell ; Ultrastructure ; Gonadal differentiation ; Cyprinus carpio (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A description is given of primordial germ cell (PGC) differentiation and gonadal development in carp from hatching until the age of 6 weeks. This period was chosen as the PGCs are mitotically silent before they start to proliferate rapidly after week 6. The PGCs increased in size between week 2 and week 4 after fertilization. Ultrastructurally, the perinuclear dense bodies present in PGCs from hatching onwards increased in size and formed the ‘cement’ between mitochondria. Moreover, from week 2 onwards, an elaborate Golgiapparatus was present in PGCs, indicating synthetic activity that may be related to PGC enlargement. During the observation period, gonadal tissue was gradually formed around the PGCs. From the age of 4 and 5 weeks onwards, two somatic cell types could be distinguished; the central type had a light appearance and was closely associated with the PGCs, the other type being darker and forming the peripheral layer of the developing gonads. Thus, during the period of mitotic quiescence, the PGCs and the gonads actively differentiate in preparation for the fast PGC proliferation that occurs after 6 weeks.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1619-7089
    Keywords: Single-photon emission tomography ; Technetium-99m hexamethylpropylene amine oxime ; Computed tomography ; Method of Mountz ; Supratentorial ischaemic infarction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A comparative interim analysis was performed of clinical parameters, computed tomographic (CT) scan results and technetium-99m hexamethylpropylene amine oxime single-photon emission tomography (SPET) findings obtained within 12 h of acute supratentorial ischaemic infarction. First, the applicability for SPET semiquantification in this study of the “method of Mountz”, simultaneously accounting for extent and degrees of hypoperfusion by expressing deficits as millilitre of zero perfusion, was considered. Next, the relative contributions of perfusion SPET and CT scan in the acute stage of ischaemic infarction were compared in 27 patients (mean age 68.8 years). Finally, the correlation of SPET lesions with clinical parameters at onset was evaluated. The method of Mountz represents a workable, accurate virtual parameter, with the assumption that the contralateral brain region remains uninvolved. Interobserver reproducibility in 12 SPET studies, with lesions varying between 6 and 369 cc, showed a correlation coefficentr of 0.99. In practice, because of inconstant distribution of activities in the brain, the method can only be applied slice by slice and not on the total global volume. While the mean delay since the onset of symptomatology was approximately 7 h for both SPET and CT scan, SPET showed lesions concordant with the clinical neurological findings in 100% and CT scan in only 48%. One could hypothesize that SPET examinations performed later would show larger functional defects, because of the development of additional functional changes secondary to biochemical alterations. However, in this regard no statistically significant differences were found between two subproups, taking the median of delay before SPET examination as cut-off. Finally, when comparing the volumes of SPET lesions during the acute stage with clinical parameters, a statistically significant correlation (P〈0.01) was found with the Orgogozo Scale scores describing the neurological deficit, but not with the Glasgow Coma Scale or Frenchay Aphasia Screening Test scores obtained on admittance.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-5168
    Keywords: larval gonad development ; primordial germ cells ; precocious spermatogenesis ; pituitary factors ; Cyprinus carpio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The data presented show that in larval carp, gonadal size has increased distinctly after treatment with homologous pituitary extract (PE). Moreover, the precocious onset of primordial germ cell proliferation and of sex differentiation into male and female gonads was induced. Body weight of treated and control specimens did not differ significantly from each other throughout the experiment. Treatment of juvenile carp with homologous PE led also to an increase in gonadal size without concomitant increase in body weight. Induction of precocious spermatogenesis was observed too. GTH-levels in control and PE-treated carp were monitored by means of a homologous radioimmunoassay, showing that in PE-treated carp the GTH-level was distinctly elevated. The possible role of pituitary hormones in larval and juvenile gonadal development is discussed.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: 3H-Thymidine incorporation experiments in Barbus conchonius showed that presumptive primordial germ cells (PGCs) terminated their mitotic activity between midepibolys, and late epiboly. At the ten-somite stage, shortly after labeling of PGCs by uptake of 3H-thymidine became arrested, they could be recognized by their relatively large size and large nucleus. They were located in two longitudinal rows of cells between mesoderm and periblast, always at the same distance to the left and right of the notochord. Contact with the endoderm was not observed before the 16- to 23-somite stage. The numbers of PGCs were small (mean number, 18-19) and remained small for nearly 3 weeks. Mitotic activity was not observed in PGCs during that period; thereafter, rapid proliferation began. There is no evidence for active migration of PGCs; it is assumed that they are merely translocated passively together with their surrounding tissues. No specific constituents were detected with histochemical methods for glycogen, alkaline phosphatase, and RNA. Electron microscopy revealed the presence of “nuage” around the nucleus of PGCs. This material corresponded with perinuclear dense bodies as seen with light microscopy from the 19-somite stage onward.It is concluded that presumptive PGCs segregate from the somatic cells between midepiboly and late epiboly, before the three germ layers have been formed, and that locations of PGCs in the endodermal or mesodermal layer may be merely transitory stages during their translocation toward the gonadal primordia.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 18 (1994), S. 853-870 
    ISSN: 0271-2091
    Keywords: Convection-diffusion problems ; Operator-splitting ; Taylor-Galerkin time integration ; Spectral element method ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Several explicit Taylor-Galerkin-based time integration schemes are proposed for the solution of both linear and non-linear convection problems with divergence-free velocity. These schemes are based on second-order Taylor series of the time derivative. The spatial discretization is performed by a high-order Galerkin spectral element method. For convection-diffusion problems an operator-splitting technique is given that decouples the treatment of the convective and diffusive terms. Both problems are then solved using a suitable time scheme. The Taylor-Galerkin methods and the operator-splitting scheme are tested numerically for both convection and convection-diffusion problems.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 22 (1996), S. 673-688 
    ISSN: 0271-2091
    Keywords: Navier-Stokes equations ; projection methods ; operator splitting ; spectral element methods ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: An approximate projection scheme based on the pressure correction method is proposed to solve the Navier-Stokes equations for incompressible flow. The algorithm is applied to the continuous equations; however, there are no problems concerning the choice of boundary conditions of the pressure step. The resulting velocity and pressure are consistent with the original system. For the spatial discretization a high-order spectral element method is chosen. The high-order accuracy allows the use of a diagonal mass matrix, resulting in a very efficient algorithm. The properties of the scheme are extensively tested by means of an analytical test example. The scheme is further validated by simulating the laminar flow over a backward-facing step.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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