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  • Male germ unit  (1)
  • Polymer and Materials Science  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 152 (1989), S. 29-36 
    ISSN: 1615-6102
    Keywords: Male germ unit ; Nicotiana tabacum ; Pollen tube ; Sperm cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The structure of sperm cells and their association with the vegetative nucleus in pollen tubes ofNicotiana tabacum grown in styles were observed with the electron microscope, demonstrating the existence of a male germ unit. The two sperm cells are arranged in tandem and are closely associated with the vegetative nucleus, which always takes the lead. The leading sperm cell (SC 1) has a long and narrow cytoplasmic projection which lies within the enclaves of the much lobed vegetative nucleus, thus forming a physical association. The trailing sperm cell (SC 2) and the SC 1 are not only joined by a common transverse cell wall but also are surrounded by a periplasm bounded by the plasma membrane of the sperm cells and that of the vegetative cell, thus forming a structural connection. The sperm cells are elongated, with cytoplasmic projections at the anterior end of the SC 1 and at both ends of the SC 2. The cytoplasm of both sperm cells includes mitochondria, endoplasmic reticulum, dictyosomes, ribosomes, small vacuoles and axially oriented microtubules. No plastids were observed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 2045-2049 
    ISSN: 0887-624X
    Keywords: pyrolysis ; GC-mass spectrometry ; maleated polyethylene ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pyrolysis-GC/mass spectrometry experiments reveal that naphthalene groups attached to maleated polyethylene as the 1-naphthylethyl ester are stable for relatively long periods of time at 170°C. Decomposition can be detected for samples heated for 2.0 min at 200°C, but even at that temperature, the extent of decomposition is very small. At higher temperatures, two of the decomposition products from the labeled polymer are readily understood: 1-vinylnaphthalene and 1-naphthylethanol can form by reactions that are well-precedented in the organic chemistry literature. At 200°C, only naphthalene is formed, which requires scission of the bond between the naphthyl ring and the C1 carbon of the ethyl group. We suggest two possible pathways for this reaction. © 1996 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 34:2045-2049, 1996
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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