RE: [Histonet] fixatives

From:Philip Oshel


There isn't a very good substitute for osmium tetroxide, but 
Maunsback and Aufzelius, "Biomedical Electron Microscopy" shows 
various fixitive alternatives, and is a good place to look. It is for 
TEM, though, and not light microscopy.
DON'T use OsO4 in a tissue processor unless it is in a **very** well 
vented fume hood and will continue so. I wouldn't use OsO4 in a 
processor period, but there are processors for EM work that do use 
it. It can be used safely, though, so I wouldn't worry about having 
in the lab, just use it properly. It does do a reasonable job 
preserving fat, but it won't prevent extract in the dehydration 
steps, especially of the unsaturated fats -- OsO4 likes to bind to 
C=C double bonds, and isn't that great a fixative for unsaturated 
lipids. Cryostat sections and no dehydration would be better.
K or NaMnO4 can work, and in the TEM it does a nice job of preserving 
membranes -- the cells can look like line drawings of the membrane 
systems. But this is because the cytoplasm is heavily extracted. Not 
what you want, I think.
Sorry I can't help with the sections-stuck-to-coverslip-tape problem, 
I've only used glass.


>Hi all:  I know this has been asked before, is there a
>quick fix for removing tissue from coverslipping tape,
>reattaching to the slide, covering with a new glass
>coverslip so the tissue can be photographed?  Also,
>does anyone know a good alertnate fixative for osmium
>tetroxide?  We are trying to keep it out of the lab.
>We have been asked to use it for a post-fix for fatty
>tissue and on an EM processor.  Thanks, Pam

Philip Oshel
Supervisor, AMFSC and BBPIC microscopy facilities
Department of Animal Sciences
University of Wisconsin
1675 Observatory Drive
Madison,  WI  53706 - 1284
voice: (608) 263-4162
fax: (608) 262-5157 (dept. fax)

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