Patricia,
                precisely what lipids are you trying to demonstrate?
Most fixing agents do not fix lipids as such although they may "preserve" them
to a limited extent oif they are associated with proteins as in lipoproteins or
proteolipids.
many lipids including phospholipids leach out from tissues during the fixation.
If you are dealing with a tissue with small amounts of lipid and the
fixation is
of relatively short duration, fixing before frozen sectioning may be desirable.
This is because the tissue around the lipid in becoming hardened, provides some
support and encloses it. If the tissue contains large amounts of lipid then
fixation may not be as helpful. In the case of blood vessels I suspect thet the
fixation will help and you shoudl be able to carry out the Sudan black
procedure. Also depends on which Sudan black method you are using
Barry

"Bourassa, Patricia" wrote:

> Hi all!
>
> One of my colleagues wants to stain rabbit aortic tissue for lipid using
> Sudan Black.  Has anyone done this?  Would there be any reason why fixation
> of the vessel before staining would interfere with the procedure?  I thought
> fixation would enhance the staining if anything (preserve morphology!!) but
> we wanted to be sure.
>
> Thanks for any info!!
>
> -Patti Bourassa
>  Pfizer, Groton

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