On Thu, 7 Oct 1999, Ken Turner wrote:

> I have a copy of Thompson, which, on page 480 gives a metanil yellow
> counterstain after PAS. The solution is: 0.25% metanil yellow in 0.25%
> acetic acid prepared with distilled water. Mix, filter and store in a clean
> brown bottle.
> After conventional periodic acid and Schiff sequence, and water washing,
> stain 1 minute in metanil yellow, rinse in distilled water, 95% ethyl
> alcohol, absolute ethyl alcohol and xylene. Thompson suggests mounting with
> Permount.

   For what it's worth, I agree 100%.  Metanil yellow provides
   a splendid yellow counterstain for cytoplasm and collagen.
   Unfortunately the dye solution is not very stable. Its colour
   changes to brown over the course of a few months, and the
   staining properties also deteriorate. I don't know why, but
   it's so. For another yellow anionic dye you might try
   tertrazine. Look it up in Bryan Llewellyn's StainsFile: a
   splendid collection of histo-wisdom.

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