[Histonet] Using chromic acid instead of periodic acid with Schiffs - for fungus staining ONLY!

[Bryan Hewlett]

What  Rita was asking about PAS-F, I don't know (what does the -F stand for 
Rita?).
However, the Bauer reaction (chromic acid oxidation-Schiff) in 1933
was the first ever use in histochemistry of a glycol to aldehyde oxidation 
reaction.
This produces a positive Schiff result in a variety of mucosubstances,
including cellulose, starch and (sorry Gayle) GLYCOGEN!
It also gives a positive result with fungal cell walls.
In fact the Bauer-Schiff was for many years the method of choice for the 
demonstration of glycogen and other mucosubstances.

As Gayle correctly pointed out, chromic acid further oxidizes the aldehydes 
, probably to carboxyl groups and then to carbon dioxide.
Mucosubstances with a high glycol density (glycogen, starch, fungal cell 
walls) are more resistant to this effect.
The resulting Schiff reaction is somewhat paler than a PAS, how much paler 
depends on oxidation time, but still positive.
Gomori (1946) used chromic acid oxidation in his method for glycogen and 
mucin(sic).
He detected the resulting aldehydes with hexamine-silver.
Grocott (1955) optimized the Gomori technique for fungal cell walls.
The Gridley stain (1953) was just a Bauer-Schiff/aldehyde fuchsine 
combination stain.
Periodic oxidation-Schiff was introduced by both Hotchkiss and McManus in 
1945-46.
Periodic acid does not further oxidize the aldehydes produced (at least not 
in any reasonable time frame) and rapidly became the oxidation-Schiff method 
of choice.

Bryan




----- Original Message ----- 
From: "Gayle Callis" <gcallis <@t> montana.edu>
To: <Histonet <@t> lists.utsouthwestern.edu>
Sent: Tuesday, August 23, 2005 6:06 PM
Subject: [Histonet] Using chromic acid instead of periodic acid with 
Schiffs - for fungus staining ONLY!


> Histonetters,
>
> I hope I didn't confuse people with my answer about PAS-F (what the F 
> meant escapes me??? for fungus, fluorescence?) where the person was asking 
> about using chromic acid instead of periodic acid i.e in PAS. 
> Theoretically, one could not call this PAS - maybe chromic acid-Schiff or 
> CAS??  The key word was the mention of Gridley staining, a method for 
> fungus staining, and I assumed this person wanted to use a chromic acid 
> oxidizer followed by Schiffs reagent for that purpose i.e fungus stain.
>
> Whatever you do, do NOT use chromic acid for a standard PAS stain if 
> staining for mucosubstances, glycogen, basement membranes or  other 
> components that are PAS positive.  Chromic acid is a much stronger 
> oxidizer than periodic acid, and will over-oxidize these components to the 
> point of them NOT staining after Schiffs application - not a good idea. 
> However chromic acid with Schiffs does work for fungus staining.  Freida 
> Carson et al wrote a publication on false negative  fungus staining by 
> using Periodic acid -Schiffs reagent, and mentioned using chromic acid in 
> place of periodic acid.  This can be found in J of Histotechnology, and an 
> excellent bit of information.
>
> Chromic acid oxidation with Schiffs reagents is reserved for those who do 
> not want use periodic acid as the oxidizing agent for fungus staining.
>
> Gayle Callis
> Research Histopathology Supervisor
> Veterinary Molecular Biology
> Montana State University - Bozeman
> PO Box 173610
> Bozeman MT 59717-3610
> 406 994-6367
> 406 994-4303 (FAX)
>
>
>
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