> > Laurie Colbert [laurie.colbert@huntingtonhospital.com] wrote:
> > Does anyone know if (and how) I can decolorize an alcian blue
> > stain so that I can restain H&E?

You should not need to decolorize alcian blue because
it generally stains things that are not stained by
either haemalum or eosin, and the turquoise colour of
alcian blue is unlikely to be confused with the blue
of haemalum or the purply-blue of haemalum followed
by eosin. _____

That said - the turquoisy-blue deposits in a section
stained with alcian blue 8G (CI 74240, Ingrain blue 1) 
are of copper phthalocyanine (CI 74160, Pigment blue 16),
formed when the soluble alcian blue stains anionic
glycoproteins or proteoglycans. The pigment is one of
the most stable of all coloured substances. It cannot be
dissolved or bleached by any reagent that would not also 
destroy any biological tissue. (The Merck Index says
it's soluble in 98% H2SO4, and also that it sublimes 
without decomposition at 580C.) 

Once a section is stained with alcian blue 8G the 
colour is there for keeps. That is one of the chief 
assets of this valuable stain. There are plenty of
ways to stain other materials after using alcian
blue, and you can be 100% confident that they won't
extract any of the AB colour. 

This is quite a large subject - lots of published 
literature has to be agonized over very carefully 
before approaching a carbohydrate identification 
challenge histochemically. The technology is well
advanced but largely unexploited. It was developed to
identify the levels of origin of mucus-secreting
tumours in the human gut, but there are many other
potential applications.
-- 
-------------------------
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1
   kiernan@uwo.ca
   http://publish.uwo.ca/~jkiernan/