On Thu, 16 Dec 1999 Immunohisto@aol.com wrote:

> I am looking for a good procedure for the PAS Alcian Blue 2.5 and what
>kindof
> control to use to get the best results. Any help would be appreciated.

  You will probably get plenty of replies, all different, both
  privately and to the HistoNet listserver in general (which is
  the correct kind of answer - so that we all learn something).

  Possibly any combination of PAS and alcian blue (pH 2.5) will
  be OK for you, but to find the best procedure you will have to
  state explicitly what questions you are trying to answer by
  using these two versatile stains. Some homework in the
  field of carbohydrate histochemistry is needed!

  Two important points to bear in mind are (1) Which stain will
  you do first? PAS-alcian blue and alcian blue-PAS do not generate
  identically coloured preparations, and for good reasons. (2) Is
  traditional PAS good enough to meet the requirements of your
  proposed investigation? There are many refinements to PAS, developed
  by the late and great P. Reid and C. Culling and others. These
  can provide considerable insight into the different sialic
  acids present in normal and abnormal mucus. There are also
  PAS variants for poly(uronic acid)s that occur in otherwise
  empty-looking extracellular space.

  If you use alcian blue only at pH 2.5 it will stain sialic and
  uronic acids as well as sulphated glycoproteins and proteoglycans.
  Staining at pH 1 will pick out the sulphated ones (mast cells,
  some gut mucus, cartilage matrix etc).

 John A. Kiernan,
 Department of Anatomy & Cell Biology,
 The University of Western Ontario,
 LONDON,  Canada  N6A 5C1