I have used a modified Gridley technique for many years to stain fungi.  It
uses a stronger oxidizer (chromic acid instead of periodic acid), which
tends to over-oxidize tissue components like glycogen, mucin, elastin,
fibrin, reticulin, basement membranes, etc., so that they no longer react
with the Schiff Reagent, leaving only the fungal structures to react. It is
therefore more specific for fungi than ordinary PAS procedures.

The original Gridley technique also employs aldehyde fuchsin to enhance the
stain; however I usually omit this step because aldehyde fuchsin stains
elastin and some other tissue components, thereby partially negating the
advantage of using chromic acid.  Particularly in tissues with abundant
elastin, like skin and lung, using aldehyde fuchsin can make it more
difficult to identify fungal hyphae, especially when they are sparse.

> ----------
> From: 	histonet-bounces@lists.utsouthwestern.edu on behalf of
> Santana, Diane
> Sent: 	Tuesday, January 24, 2006 12:10 PM
> To: 	'histonet@lists.utsouthwestern.edu'
> Subject: 	[Histonet] pas
> 
> Hi,
> I am just curious on how others are doing a PAS for fungus?
> Thanks 
> Diane Santana
> 
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