Dear Colin,
we usually used 10% Neutral Buffered Formalin for cell buttons and FNA's;
fixation time is anything from 10mins to 2hrs depending upon urgency, in any
case the first two pots in our processor are 10%NBF of ten minutes each on
our rapid three hour cycle. For those very bloody specs. that might obscure
detail, we fix the material in Carnoy's fixative Mod. to lyse the red cells
for not more than twenty minutes; after this time Nuclear detail is damaged.
PLease note that you should not get Formalin pigment in correctly buffered
10%NBF, if you do so, then the buffer capacity of the solution has been
exceed either through using an insufficient volume of fixative or by using
an inadequate buffering system, if you wish to be alerted to early changes
in your fixative that indicate the capacity is being exceed then add an
indicator such as Bromothymol Blue whcih is Green at pH 7.0 and will go
yellow at about 6.5 long before pH 5.8 at or about which you begin to from
formalin pigment.
The exceeding of buffer capacity is most likely with Haemopoetic tissues,
and also thyroid and Liver.
Yours sincerely Mike (Downunder)
-----Original Message-----
From: Colin Henderson <COLINH@stj.stjosephs.london.on.ca>
To: HistoNet@Pathology.swmed.edu <HistoNet@Pathology.swmed.edu>
Date: Friday, 22 January 1999 7:07
Subject: Cell Button Fixatives


>Histonet:
>
>I am looking for a rapid fixative for fine needle
>aspirations which will:
>
>1) avoid formalin pigment artefact (the fluids are often
>    very hemorrhagic)
>
>and
>
>2) quickly harden up the spun down cellular
>    component of the aspirate (cell button) so that
>    we can process it the same day
>
>Thanks in advance
>
>Colin in London, Ontario, Canada
>