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  • 1970-1974  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructural aspects of cell wall synthesis inSpirogyra (1970)
    Springer
    Protoplasma 69 (1970), S. 405-416 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Filaments ofSpirogyra were fixed in 2% osmium tetroxide dehydrated in alcohol and embedded in Araldite. The fine structure of cells with regard to wall synthesis was studied. The cell wall was shown to have four layers. The inner one contains microfibrils and is considered to be the cell wall proper. The outer three layers are components of the slime layer. The innermost of these, the second layer of the wall, was shown to be between 1μm to 3μm and the third 0.3μm to 1μm. The fourth layer appears as no more than a dark black line measuring 10 nm across. In the cytoplasm two types of vesicles were seen. The largest of these has contents similar in appearance to the slime layer of the wall. This same material was also seen in the large vesicles attached to the Golgi bodies. It is suggested that the smaller vesicles are derived from the larger vesicles and later fuse with the cell membrane. The Golgi bodies were found to be fairly large measuring up to 5μm across. Small electron opaque blobs and flecks on the outside of the plasmalemma and in between the microfibrils of the cell wall proper are considered to be mucilage droplets travelling to the slime layer. It cannot be excluded that some of the material of the large vesicles is released directly into the cytoplasm and is transferred without vesicles through the plasma membrane. The negative contrast appearance of the microfibrils seen in the cell wall is thought to be due to the spaces between them being filled with this electron opaque mucilage. Intercisternal rodlets measuring 2.5 nm across were seen in the Golgi bodies. Transverse microtubules were found to occur near the plasmalemma having the same orientation as some of the microfibrils. Lomasome-like structures sometimes with many 5 nm fibrils in their vicinity were seen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01320304
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  • 2
    Electronic Resource
    Electronic Resource
    Nuclear envelope projections from pronuclei ofSpirogyra zygotes (1974)
    Springer
    Protoplasma 79 (1974), S. 31-40 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Spirogyra zygospores were fixed in buffered 2% osmium tetroxide and embedded in Epon. Serial sectioning established that the pronuclei, in the zygotes studied, had come to lie in very close proximity but had not started to fuse. The pronuclei had interesting projections from their nuclear envelopes. These were regular finger-like structures containing both membranes of the nuclear envelope but lacking nuclear pores. The projections measured 0.22 μm in diameter and had an indeterminate length around 2.0 μm. They had an inner band on the nucleoplasmic side which appeared to describe a helix along the evagination maintaining a distance of 20 nm from the inner membrane, except for occasional small regions of contact. The possibility that these evaginations were important in nuclear movement or fusion was considered less likely than that they were involved in some kind of nucleocytoplasmic exchange, possibly organellogenesis like that described inPteridium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02055781
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    Paper (German National Licenses)
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