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Thread: Cell wall visible/not visible?

  1. #1 Cell wall visible/not visible? 
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    Here is an example of some onion cells: http://biology.clc.uc.edu/Fankhauser...d_PA021960.JPG

    I can see the cell wall surrounding each cell quite clearly. How come i can see into this cell (i.e. nucleus, cytoplasm) if a cell wall is covering it? Why can i see through the cell wall when i look down on it, but I can't see through it on the sides of the cell?


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  3. #2  
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    the cell wall is semi transparent perhaps?


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  4. #3  
    Forum Cosmic Wizard paralith's Avatar
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    Because you're looking at a cross section. To do immunohistochemical staining, you cut your sample into micro-meter thin sections, against the grain of the cells, so that you get flat cross sections, and then you put them on a slide.
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  5. #4  
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    I've looked at onion cells simply by peeling off a thin layer from its inside (then staining them and so on). Does this create a cross section?

    Then does this mean that we have cut the cell in half by peeling the layer? If so, have we also taken off part of the membrane, and then why doesn't the cell leak (without a full membrane)?
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  6. #5  
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    No I think you're all missing the point, the cell wall is thickest at the edges because you're looking at more molecules of cell wall, its thinner when you look into the cell because your looking at a lamina of the wall so its more transparent.

    ye you could have removed the membrane from some of the but they would still remain largely in the same position as the matrix of cells is quite tight.
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  7. #6  
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    Sorry, I don't quite understand. What do you mean when you say "your looking at a lamina of the wall so its more transparent."
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  8. #7  
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    Take a sheet of glass you can see right through it, now look through it from edge to edge, (it usually appears dark green with very little light travelling right through). Imagine a cell as a cube made from six glass sheets, when you look down on it, you can see through the roof and floor but not nearly so well through the 'walls' put lots of these cells together and you get the same effect as in your picture above.
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  9. #8  
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    Exactly good analogy.
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  10. #9  
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    Thanks, I get it now, although there is one query that leads me onto another question. What if the cell were spherical or cylindar? (Although, could this be possible due to the nature of a cell wall?) Would we be able to see the cell wall of a spherical/cylindar cell through a light microscope?
    For taking your glass analogy, if it were a glass ball i dont expect we would see the sides definitively, and if we did it would be a gradient colour[?] For example, colourless glass fading into dark green towards the sides of the cell. Would we see this fading in spherical cells with cell walls under a light microscope rather than the definitive lines we see in the onion cells?

    [I'm not sure if that fading analogy is right because i dont have a glass ball to check.]
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  11. #10  
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    Of course, but it will not be as well defined. I believe spherical cells are more or less restricted to early development of muli-cellular beings or to perhaps some single cell structures. But that's way outside my limit.

    In a multicellular orgasm I am not sure you can have a structure made of spherical cells, this might imply 'gaps' or 'voids' ???
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