Do you oxidize with same % chromic as for GMS? And for same amount of time?
Thanks, j
Joyce Weems
Pathology Manager
Saint Joseph's Hospital of Atlanta


	-----Original Message-----
	From:	Gayle Callis [SMTP:uvsgc@msu.oscs.montana.edu]
	Sent:	Wednesday, February 09, 2000 3:32 PM
	To:	histonet@pathology.swmed.edu
	Subject:	GMS/periodic acid/chromic acid

	Pneumocystis is not a fungi, but does stain with GMS,  

	Periodic acid may work for some fungi, but is a weak oxidizing
agent, compared to Chromic acid.

	I never had good success with it, and some fungi might not stain as
well after using the PA, in
	lieu of chromic acid.

	Even when using Schiff's reagent for strong staining of fung, the
chromic acid is used as an 
	oxidizer.

	Caveat here, calling this combination a PAS is not true, it is a
chromic acid-Schiffs.

	I think there was discussion about this a year ago, or so on
HIstonet.  and there may be a
	publication lurking around, as I recall???? in Journal of
Histotechnology.  

	Beware of creating a false negative because of using of weaker
periodic acid oxidizer, 
	you might miss something -  a fungi wall better oxidized by chromic
acid.  

	Gayle Callis