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  • Articles  (3)
  • 2020-2022  (2)
  • 1980-1984  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurocytology 10 (1981), S. 805-818 
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A quantitative light microscopic analysis of the ventral grey matter in the lumbar spinal cord of homozygous nude (nu/nu) and heterozygous (nu/+) mice was performed to determine the possible contribution of lymphocytes to normal C.N.S. tissue. If lymphocytes were present in the neuropil, they could be mistaken for neuroglial cells. Athymic nude mice offer a good model, since they lack T-lymphocytes and symptoms of neurological involvement. Mean cell counts from 1 μm sections were tested by analysis of variance. There were no strain differences for the area and number of neurons. The total neuroglial cell count was also similar, but the number of oligodendrocytes decreased 28%, astrocytes increased 51% and microglia were unchanged in the nude compared with the heterozygous mouse. There were no qualitative differences at the ultrastructural level among the neuroglia of either strain. Either the genetic defect retards and alters neuroglial cell development, or some of the small, round dark nuclei belong to lymphocytes, which have earlier migrated into the C.N.S. parenchyma. Lymphocytes could then participate in a cell-mediated immune response with brain macrophages, which are thought to be primarily derived from mononuclear leukocytes.
    Type of Medium: Electronic Resource
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  • 2
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    In:  EPIC3EGU General Assembly 2020, 2020-05-04-2020-05-08Dissolved Neodymium Isotopes Trace Origin and Spatiotemporal Evolution of Modern Arctic Sea Ice
    Publication Date: 2021-07-27
    Description: The lifetime and thickness of Arctic sea ice have markedly decreased in the recent past. This affects Arctic marine ecosystems and the biological pump, given that sea ice acts as platform and transport medium of marine and atmospheric nutrients. At the same time sea ice reduces light penetration to the Arctic Ocean and restricts ocean/atmosphere exchange. In order to understand the ongoing changes and their implications, reconstructions of source regions and drift trajectories of Arctic sea ice are imperative. Automated ice tracking approaches based on satellite-derived sea-ice motion products (e.g. ICETrack) currently perform well in dense ice fields, but provide limited information at the ice edge or in poorly ice-covered areas. Radiogenic neodymium (Nd) isotopes (εNd) have the potential to serve as a chemical tracer of sea-ice provenance and thus may provide information beyond what can be expected from satellite-based assessments. This potential results from pronounced εNd differences between the distinct marine and riverine sources, which feed the surface waters of the different sea-ice formation regions. We present the first dissolved (〈 0.45 µm) Nd isotope and concentration data obtained from optically clean Arctic first- and multi-year sea ice (ice cores) collected from different ice floes across the Fram Strait during the RV POLARSTERN cruise PS85 in 2014. Our data confirm the preservation of the seawater εNdsignatures in sea ice despite low Nd concentrations (on average ~ 6 pmol/kg) resulting from efficient brine rejection. The large range in εNd signatures (~ -10 to -30) mirrors that of surface waters in various parts of the Arctic Ocean, indicating that differences between ice floes but also between various sections in an individual ice core reflect the origin and evolution of the sea ice over time. Most ice cores have εNd signatures of around -10, suggesting that the sea ice was formed in well-mixed waters in the central Arctic Ocean and transported directly to the Fram Strait via the Transpolar Drift. Some ice cores, however, also revealed highly unradiogenic signatures (εNd 〈 ~ -15) in their youngest (bottom) sections, which we attribute to incorporation of meltwater from Greenland into newly grown sea ice layers. Our new approach facilitates the reconstruction of the origin and spatiotemporal evolution of isolated sea-ice floes in the future Arctic.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 3
    Publication Date: 2021-10-01
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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