DEar Natalie et al.,
 
I'm not an expert in this area, but from some experience looking at living
cells under various conditions (LM, fluorescence, confocal), any cell
exposed too long to the light source, or observed at too high an intensity
will eventually give up the ghost.  Cells under confocal seem somewhat more
prone to this, I guess because the laser is pretty intense.
 
Aldehyde fixation is an interesting one.  We've found that with brief
fixation in paraformaldehyde, or brief incubation in detergent, plant cells
are permeabilised to some extent, but they can still be plasmolysed by
highly osmotic solutions.  I don't know if this occurs in animal cells (no
vacuole) but it does indicate that membranes can be relatively intact yet
still let large molecules through.
 
another 1=A2 worth...
 
 
Rosemary White
Department of Ecology and Evolutionary Biology
Monash University, Clayton, Victoria 3168, Australia
phone  61-3-9905 5670    email  [log in to unmask]
fax    61-3-9905 5613       or  [log in to unmask]