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  • 1985-1989  (6)
  • Impatiens sultani  (2)
  • Sperm  (2)
  • Ultrastructure  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Pre-fertilization degeneration of both synergids in Brassica campestris ovules (1988)
    Springer
    Sexual plant reproduction 1 (1988), S. 208-216 
    Details
    ISSN: 1432-2145
    Keywords: Megagametophyte ; Synergids ; Brassica campestris ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Brassica campestris, both synergids of the ovule degenerate before the arrival of the pollen tube. Synergid degeneration does not depend on pollination. At the non-degenerated stage, the synergids are completely filled with a complexly organized cytoplasm containing numerous mitochondria with many cristae, a large number of dictyosomes with many associated vesicles, and a very extensive rough endoplasmic reticulum. The degenerative changes that occur in the cytoplasm of the synergids are characterized by a loss of visibility of the membranes of the endoplasmic reticulum and the simultaneous formation of dense deposits on the surrounding membranes of the mitochondria. Locally, the plasma membranes of the synergids disappear, and some ground plasma of the synergids penetrates into the space between the plasma membranes of the egg cell and the central cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00189154
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Cytokinesis in microspore mother cells of Impatiens sultani (1988)
    Springer
    Sexual plant reproduction 1 (1988), S. 228-233 
    Details
    ISSN: 1432-2145
    Keywords: Microspore mother cell ; Cytokinesis ; Impatiens sultani ; Cell plate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cytokinesis in Impatiens sultani microspore mother cells is simultaneous. It starts with the formation of small ingrowths of the surrounding callosic wall. Next, an incomplete cell plate is formed by fusion of small dictyosome vesicles. The cell plate consists of a network of anastomosing tubules and sacs. Aggregates of fusing vesicles are associated with bundles of microtubules, which are oriented perpendicular to the plane of the future cell walls. In the sacculate parts of the cell plate, some callose is deposited, while the associated microtubules disappear. The cell walls ultimately develop by enlargement of the previously formed wall ingrowths, which successively incorporate the elements of the cell plate. The enlargement and thickening of the walls is not accompanied by a further fusion and incorporation of dictyosome vesicles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00189157
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The ultrastructure of polymorphic pollen grains of Canna indica L. (1989)
    Springer
    Sexual plant reproduction 2 (1989), S. 193-198 
    Details
    ISSN: 1432-2145
    Keywords: Polymorphism ; Ultrastructure ; Pollen grains ; Canna indica L ; Tannin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Our investigations on Canna indica L. indicate that the pollen of this species is polymorphic: there are two types of pollen — a larger type and a comparatively smaller type. Transmission electron microscopy (TEM) revealed the presence of small vacuoles containing tannic substances in the generative cell (GC) of the larger grains: the GC of the mature grain contained a higher quantity of tannins than the GC of the immature grain. Mitochondria, lipid bodies, rough endoplasmic reticulum (RER) and microtubular bundles were present in the cytoplasm of the GC. Numerous mitochondria, lipid bodies and plastids were also present in the vegetative cell (VC), with the mitochondria clustered around the vegetative nucleus. The plastids were observed to be associated with the RER cisterns. During the maturation process, the number of starch grains contained in the plastids decreased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192766
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Cytoskeletal changes during generative cell division and sperm formation inTradescantia virginiana (1989)
    Springer
    Protoplasma 150 (1989), S. 54-71 
    Details
    ISSN: 1615-6102
    Keywords: Generative cell ; Microtubules ; Mitosis ; Cytokinesis ; Pollen ; Sperm ; Tradescantia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cytoskeletal organization and chromosome behavior were studied inTradescantia generative cells prior to and during sperm formation using in vitro grown pollen tubes and fluorescence staining methods. Before pollen germination, the crescent-shaped generative cell contains a reticulate microtubule (Mt) system. The cell elongates dramatically after germination, and its Mts assume a helical to longitudinal arrangement. Chromosome condensation is evident approximately 3hr after germination. Kinetochores appear as dark interruptions in the Mt array, and thus seem to attach directly to interphase fibers. No metaphase plate typical of other cells is observed with either DAPI or anti-tubulin staining. Instead, the chromosomes adopt a twisted or braided arrangement, with kinetochores distributed along the length of the cell and kinetochore fibers linked to each other and to surrounding fibers. Anaphase is characterized by a staggered, overlapping separation of chromosomes and by elongation of Mt branches connecting opposing kinetochore fibers. Cytokinesis appears to utilize a furrowing process; a phragmoplast or cell plate was never seen. As a result of these events, the sperm directly inherit their cytoskeleton from generative cell Mts involved in division. No actin fibers are observed at any stage using rhodamine-phalloidin staining. The results are discussed in terms of other reports on sperm formation, possible mitotic and cytokinetic mechanisms, and past distinctions between Mt arrays in higher plant somatic cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01352921
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  • 5
    Electronic Resource
    Electronic Resource
    Microtubule organization in the sperm ofTradescantia virginiana (1988)
    Springer
    Protoplasma 146 (1988), S. 28-34 
    Details
    ISSN: 1615-6102
    Keywords: Generative cell ; Microtubule ; Sperm ; Pollen ; Tradescantia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Microtubules were visualized in the sperm ofTradescantia virginiana pollen tubes grownin vitro and processed for antitubulin immunocytochemistry. The sperm contain thick microtubule bundles from which emerge numerous branches of various dimensions disposed longitudinally and helically along the cell axis. Sperm are usually spindle or cigar-shaped, but cells of various sizes and shapes can be found. All contain microtubule arrays. No F-actin was detected in sperm using rhodamine-phalloidin staining. Sperm microtubules are discussed in terms of their potential roles in cell shaping and motility and their origin during generative cell division.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01354292
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Cytoplasmic differentiation during tetrad formation and early microspore development inImpatiens sultani (1989)
    Springer
    Protoplasma 148 (1989), S. 1-7 
    Details
    ISSN: 1615-6102
    Keywords: Microspore mother cell ; Microspore ; Impatiens sultani ; Cytoplasm ; Organelles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary From early prophase stage until probaculae formation within the tetrad stage considerable cytoplasmic changes occur. The changes merely concern the ribosome population, the plasma matrix and, the endomembrane system formed by endoplasmic reticulum, dictyosomes and dictyosome-vesicles. The ultrastructure and morphology of mitochondria and plastids remain fairly unchanged, apart from the mobilization of starch during primexine formation. During meiotic prophase there is an increase in ribosome number, accompanied by the presence of nucleoloids in the cytoplasm. Simultaneously the electron density of the cytoplasm strongly increases, indicating a fair increase in protein content. Nucleoloids are also observed in the cytoplasm after primexine formation, accompanied by localized accumulation of ribosomes. Up to the individualization of the microspores the dictyosomes are in an inactive state. After that, they become very active, especially during primexine formation when numerous large dictyosome-vesicles are present. The endoplasmic reticulum (ER), initially in a plate-like configuration, disappears from the cytoplasm during primexine formation. Abundant, smooth and tubular ER is present when probaculum formation starts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01403985
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    Paper (German National Licenses)
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