Jennifer,

		There are a few possibilities for this precipitate without
actually seeing it. It does not sound as if the problem is with the tissue
or  the acid fast organism, but with an exogenous contaminant. Carbol
fuchsin, being a saturated alcoholic solution of basic fuchsin with phenol,
can cake if exposed to excess heat or steam. The carbol fuchsin can also
clump if basic fuchsin is added too quickly to the alcoholic solution. If
properly prepared and stored the solution can last for years.

	1. Carbol fuchsin was not adequately mixed and filtered.
		2. Prolonged heating of the carbol fuchsin during staining
caused the basic fuchsin to precipitate from evaporation and was not
sufficiently decolorized by the acid alcohol.
	3. Talc (French chalk ) from gloves contaminating deparaffinized
slides and staining with carbol fuchsin.

	Eric Kellar
	Histology/Immunohistochemistry
	University of Pittsburgh Medical Center


	----------
	From: 	Berger, Jennifer[SMTP:jberger@lrri.org]
	Sent: 	Friday, February 19, 1999 5:36 PM
	To: 	'histonet'
	Subject: 	Carbol Fushin for AFB

	A co-worker of mine is getting ready for her practical for histo
	certification and she tried staining TB positive monkey lung tissue
with
	Ziehl-Neelsen Carbol Fuchsin and she got some kind of precipitate on
the
	slides, the precipitate is purplish-black and almost perfectly
round. Any
	ideas??
	I guess she needs to stain tissue with Acid Fast Bacteria with
Carbol
	Fuchsin.
	I hope this makes sense to someone, as you can tell I am not in the
	histology lab.
	Jennifer