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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Virchows Archiv 409 (1986), S. 251-261 
    ISSN: 1432-2307
    Schlagwort(e): Erythrophagocytosis ; Erythropoiesis ; Hypoxia ; Splenic red pulp
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In rats chronic hypoxia causes extramedullary haematopoiesis mainly localized in the spleen. It is not known how splenic erythropoiesis develops and how it regresses after termination of hypoxia. In this study the spleen of rats exposed to chronic hypoxia was studied by light and electron microscopy; the findings were compared to relevant peripheral blood values. Splenic erythropoiesis begins almost immediately after exposure to hypoxia and reaches its maximum after 24 weeks. It occurs mainly in the splenic cords drawing upon local erythroblasts and is accompanied by an increase in splenic weight as well as a decrease in splenic iron stores. After termination of hypoxia marked phagocytosis by splenic cord macrophages diminishes the number of erythroblasts and of erythrocytes with a concomitant increase in splenic iron stores. Thus, splenic erythropoiesis appears to be inhibited as part of a rebound phenomenon and returned to normal by phagocytosis of erythroid cells within 4 weeks after cessation of the hypoxic stimulus.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 157 (1993), S. 65-74 
    ISSN: 1573-5036
    Schlagwort(e): root distribution ; shoot growth ; soil structural discontinuity ; water use
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The role of roots penetrating various undisturbed soil horizons beneath loose layer in water use and shoot growth of maize was evaluated in greenhouse experiment. 18 undisturbed soil columns 20 cm in diameter and 20 cm in height were taken from the depths 30–50 cm and 50–70 cm from a Brown Lowland soil, a Pseudogley and a Brown Andosol (3 columns from each depth and soil). Initial resistance to penetration in undisturbed soil horizons varied from 2.5 to 8.9 MPa while that in the loose layer was 0.01 MPa. The undisturbed horizons had a major effect on vertical arrangement of roots. Root length density in loose layer varied from 96 to 126 km m-3 while in adjacent stronger top layers of undisturbed horizons from 1.6 to 20.0 km m-3 with higher values in upper horizons of each soil. For specific root length, the corresponding ranges were 79.4–107.7 m g-1 (on dry basis) and 38.2–63.7 m g-1, respectively. Ratios of root dry weight per unit volume of soil between loose and adjacent undisturbed layers were much lower than those of root length density indicating that roots in undisturbed horizons were produced with considerably higher partition of assimilates. Root size in undisturbed horizons relative to total roots was from 1.1 to 38.1% while water use from the horizons was from 54.1 to 74.0%. Total water use and shoot growth were positively correlated with root length in undisturbed soil horizons. There was no correlation between shoot growth and water use from the loose layers.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 157 (1993), S. 65-74 
    ISSN: 1573-5036
    Schlagwort(e): root distribution ; shoot growth ; soil structural discontinuity ; water use
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The role of roots penetrating various undisturbed soil horizons beneath loose layer in water use and shoot growth of maize was evaluated in greenhouse experiment. 18 undisturbed soil columns 20 cm in diameter and 20 cm in height were taken from the depths 30–50 cm and 50–70 cm from a Brown Lowland soil, a Pseudogley and a Brown Andosol (3 columns from each depth and soil). Initial resistance to penetration in undisturbed soil horizons varied from 2.5 to 8.9 MPa while that in the loose layer was 0.01 MPa. The undisturbed horizons had a major effect on vertical arrangement of roots. Root length density in loose layer varied from 96 to 126 km m-3 while in adjacent stronger top layers of undisturbed horizons from 1.6 to 20.0 km m-3 with higher values in upper horizons of each soil. For specific root length, the corresponding ranges were 79.4–107.7 m g-1 (on dry basis) and 38.2–63.7 m g-1, respectively. Ratios of root dry weight per unit volume of soil between loose and adjacent undisturbed layers were much lower than those of root length density indicating that roots in undisturbed horizons were produced with considerably higher partition of assimilates. Root size in undisturbed horizons relative to total roots was from 1.1 to 38.1% while water use from the horizons was from 54.1 to 74.0%. Total water use and shoot growth were positively correlated with root length in undisturbed soil horizons. There was no correlation between shoot growth and water use from the loose layers.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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