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  • 1
    Electronic Resource
    Electronic Resource
    Cyclosporin-A Differentially Affects Apoptosis During In Vivo Rat Thymocyte Maturation (2002)
    Oxford, UK : Blackwell Science Ltd
    Scandinavian journal of immunology 56 (2002), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Maturation arrest and interference with selection are two well-documented effects of cyclosporin-A (CsA) on the thymus. We recently hypothesized that these effects are related and owing to the reduced T-cell receptor (TCR)–CD3 complex-mediated signal transduction in thymocytes upon CsA treatment. In this hypothesis, the maturation arrest is the result of the additional depletion of thymocytes that normally survive by positive selection, whereas the impaired self-tolerance induction is caused by an increased survival of thymocytes that normally undergo negative selection. In this view, it is anticipated that CsA differentially affects thymocyte apoptosis during in vivo thymocyte maturation. Indeed, we report in this study a strong increase in apoptotic cells in the thymic cortex on in situ analysis. Simultaneously, the number of apoptotic cells had decreased at the cortico-medullary zone which is held to be the site for negative selection. Rapamycin (Rapa) also interferes with thymocyte maturation by inhibiting cytokine-driven proliferation. Hence, Rapa preferentially affects the early maturational stages of thymocyte development and is considered not to alter thymocyte selection and subsequent apoptotic events. Indeed, the number of apoptotic events appears not to be altered. However, possibly owing to the decrease in cortical macrophages, the apoptotic cells revealed an atypical enumeration around blood vessels. Taken together, our results favour the hypothesis that the dominant effect of CsA on the thymus is the reduction of the TCR–CD3 complex-mediated signal transduction in thymocytes upon interaction with stromal cells. Furthermore, the preferential localization of apoptotic cells next to blood vessels upon Rapa administration may indicate that endothelial cells are a back-up system for the removal of apoptotic cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3083.2002.01110.x
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  • 2
    Electronic Resource
    Electronic Resource
    At the cutting edge biosynthesis and paracrine/cryptocrine actions of 'self' neurohypophysial-related peptides in the thymus
    Amsterdam : Elsevier
    Molecular and Cellular Endocrinology 76 (1991), S. C27-C31 
    Details
    ISSN: 0303-7207
    Keywords: 'Self' peptide ; Autoimmunity ; Cryptocrine ; Developmental biology ; Neuroimmunomodulation ; Neuropeptide ; Nurse cell ; Thymus
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0303-7207(91)90277-Y
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  • 3
    Electronic Resource
    Electronic Resource
    Graft of autologous fibroblasts in gingival tissue in vivo after culture in vitro preliminary study on rats (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 34 (1999), S. 0 
    Details
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Several grafting techniques and guided tissue regeneration techniques (GTR) have been well-developed in periodontal surgery. However, these techniques could induce pain and side effects, such as a gingival recession during the healing period following the therapy. The graft of a small autologous connective tissue, using non-invasive surgical techniques could yield several benefits for the patients. Our preliminary study explores the feasibility of collecting healthy gingival tissues, culturing them in vitro to amplify rat gingival fibroblasts (RGF) and inoculating the obtained cells into autologous rat gingival tissues in vivo. Gingival tissues samples were cultured as explains as described by Freshney et al. and Adolphe. Confluent cells surrounding explants were detached after 7 d of culture from Petri dishes using 0.05% trypsin and designated “first transferred cells” (T1). At the third passage (T3), cells cultured as monolayer were either examined under microscopy - phase contrast, scanning, or transmission electron - or numerated after trypan blue exclusion test. Autologous RGF labelled with fluorochrome were inoculated at the vestibular and palatine site of gingival tissue close to the superior incisors. In this preliminary study, 12 Wistar rats were used; for each, 2 biopsies were dissected and fixed for phase contrast or fluorescence microscopy. On d 1, 3 and 7 after injection in rat gingival tissues, fluorochrome-labelled cells could be detected in all these.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0765.1999.tb02260.x
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  • 4
    Electronic Resource
    Electronic Resource
    Distribution of Lyt antigens on the surface of thymocytes associated with thymic macrophages and dendritic cells (1988)
    Springer
    Histochemistry and cell biology 88 (1988), S. 553-556 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Thymocyte subpopulations that are associated with macrophages and dendritic cells of the thymus in vivo were isolated from the thymuses of C57Bl/6 mice, and their Lyt phenotypes were analyzed. Electron-microscopic examination of immunogold-labeled cells revealed that the thymic complexes formed by macrophages mainly contained Lyt-2-positive thymocytes, while Lyt-1-positive thymocytes were more frequently associated with dendritic cells. The characteristic distributions of Lyt antigens on the surface of thymocytes in regions of reciprocal contact with macrophages (Lyt-2-positive cells) and dendritic cells (Lyt-1-positive cells) suggest that these antigens play a role in specific interactions between thymocytes and stroma cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570323
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  • 5
    Electronic Resource
    Electronic Resource
    The ER-TR4 monoclonal antibody recognizes murine thymic epithelial cells (Type 1) and inhibits their capacity to interact with immature thymocytes: immuno-electron microscopic and functional studies (1994)
    Springer
    Histochemistry and cell biology 101 (1994), S. 355-363 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The thymic stroma is heterogeneous with regard to cellular morphology and cellular function. In this study, we employed the monoclonal antibody ER-TR4 to characterize stromal cells at the ultrastructural level. To identify the labelled cell type, we used two techniques: immunogold labelling on ultrathin frozen sections and immunoperoxidase staining on thick “vibratome” sections. ER-TR4 reacted with thymic Type 1 epithelial cells (according to our classification). A dense labelling appears in the cytoplasm of cortical cells using the two techniques. Immunogold labelling identified small cytoplasmic vesicles whereas the cytoplasm and the cell membrane seem to be labelled with the immunoperoxidase technique. ER-TR4 also identified isolated thymic nurse cells (TNC), and was observed in vitro to inhibit the capacity of some type 1 epithelial cells to establish interactions with immature thymocytes. This finding supports the hypothesis that the factor is involved in the formation of lymphoepithelial interactions within thymic nurse cells, and thus in the relations that immature thymocytes establish with the thymic microenvironment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00268997
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  • 6
    Electronic Resource
    Electronic Resource
    Thymic microenvironment and cultures derived from mouse thymic explants (1981)
    Springer
    Cell & tissue research 214 (1981), S. 431-441 
    Details
    ISSN: 1432-0878
    Keywords: Thymus ; Microenvironment ; Culture ; Epithelial cells ; Macrophages
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cultures derived from thymus fragments of embryonic (18–19 day old), newborn or one month old C57 BL mice have been characterized functionally (phagocytic and nonspecific esterase activities) and morphologically by means of light, scanning (SEM) and transmission (TEM) electron microscopy. The observations show the heterogeneity of the cell populations composing the monolayers. After a few days incubation macrophages appear as the predominating cell type, while epithelial cells usually constitute no more than 30% of the cells. Experiments designed to determine the fate of lymphocytes adhering to the monolayers lead us to believe (on the basis of SEM morphometric analysis) that the survival of lymphocytes attached either to thymic macrophages or to epithelial cells is improved during the first days of coculture. This survival enhancement does not, however, appear to be a specific inductive effect since a similar survival increase is found when lymphocytes adhere to non-thymic cells. In contrast with the monolayer, the expiant provides a three-dimensional culture system able to preserve intact thymic microenvironmental conditions since numerous lymphocytes are found even in five week old cultures which were not overlaid with thymocytes or spleen cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249223
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