Ooh, great question for my students next semester.
Your answer is the counterstain, some counterstains may require dehydration
after rinsing, or some may not. Adjusting the times of the counterstain is not
the issue as much as the solvent of the counterstain.
Rene, while I do acknowledge that the xylene may/will cause hazards, we must
think of the miscibility of the clearant and the dehydrant, as well as the
amount of time involved. The amount of time involved to blot and air dry the
slides will affect the TAT for the specimen. 5 min may be ok if you have a
small amount of slides, but with a larger number of slides, it will be
considerably more than 5. Also Lean methodologies would not apply in that
case. With automation, the extreme heat involved with a stain dryer may affect
the tissue on the slide.
There are some stains that can be blotted, cleared and coverslipped, but using
the alcohol to remove excess water and counter stain is better in my opinion.
Toysha N. Mayer, MBA, HT (ASCP)
Instructor, Education Coordinator
Program in Histotechnology
School of Health Professions
MD Anderson Cancer Center
(713) 563-3481
tnma...@mdanderson.org
Message: 16
Date: Tue, 11 Sep 2012 10:32:08 -0400
From: "Diana McCaig" <dmcc...@ckha.on.ca>
Subject: [Histonet] air drying special stain slides rather than
dehydrate and clear
To: <histonet@lists.utsouthwestern.edu>
Message-ID:
<dcfd9e6a390e294aaf3a2561cd32e5c417a90...@ckhamail1.ckha.on.ca>
Content-Type: text/plain; charset="us-ascii"
I was hoping to get information on why special stains are dehydrated, cleared
and mounted vs allowing them to be blotted dry, air dried then coverslip.
Every procedure I have ever encountered always indicates to dehydrate and clear
but I have heard where some labs are blotting the slides , allowing to air dry
(probably not set standard time) and dipped in xylene prior to cover slipping.
Reason given is that the counterstain gets washed out. Wouldn't adjusting the
times be a better resolution.
I understand residual water could be present and cause long term issues on
storage but wanted some other opinions on this process.
Diana
------------------------------
Message: 17
Date: Tue, 11 Sep 2012 07:52:05 -0700 (PDT)
From: Rene J Buesa <rjbu...@yahoo.com>
Subject: Re: [Histonet] air drying special stain slides rather than
dehydrate and clear
To: Diana McCaig <dmcc...@ckha.on.ca>,
"histonet@lists.utsouthwestern.edu"
<histonet@lists.utsouthwestern.edu>
Message-ID:
<1347375125.72189.yahoomail...@web121405.mail.ne1.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1
Diana:
The most simple answer to your question is: "Because that is the way it has
been done for more than 150 years".
The second question would be: "Is it necessary?" and the short answer to this
question is: NO!!!
As a matter of fact, one of the steps I have developed to totally eliminate
xylene from the histology lab refers to the "clearing" of stained sections, not
only "special stains" (the so called HC and IHC) but the routine as well (the
H&E).
Now, the "secret" to a successful drying of the stained slides is NOT to let
them air dry because that will take not only too much time, but you can never
be sure if the section is completely dry and if you add the mounting medium to
a not completely dried section, you will have transparency problems.
The correct way of doing that is by drying the stained sections during 5
minutes at 60?C in an oven.
Under separate cover I am sending you something I published about your question
and other aspects of how to completely eliminate xylene from ALL steps in the
histology laboratory.
Ren? J.
________________________________
From: Diana McCaig <dmcc...@ckha.on.ca>
To: histonet@lists.utsouthwestern.edu
Sent: Tuesday, September 11, 2012 10:32 AM
Subject: [Histonet] air drying special stain slides rather than dehydrate and
clear
I was hoping to get information on why special stains are dehydrated, cleared
and mounted vs allowing them to be blotted dry, air dried then coverslip.
Every procedure I have ever encountered always indicates to dehydrate and clear
but I have heard where some labs are blotting the slides , allowing to air dry
(probably not set standard time) and dipped in xylene prior to cover slipping.?
Reason given is that the counterstain gets washed out.? Wouldn't adjusting the
times be a better resolution.
I understand residual water could be present and cause long term issues on
storage but wanted some other opinions on this process.
Diana
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