SPAM-LOW: [Histonet] air dry or heat dry

Patsy Ruegg pruegg <@t>
Sat Jul 10 11:48:21 CDT 2010

I really do not think it is a good idea to heat frozen sections, especially
repeatedly.  I air dry frozen sections, then store them in slide mailers
(holds 5) in plastic bags at -80. Take what ever slide mailers I need and
put them in a plastic bag I store in the freezer which has some desiccant in
it and seal it.  I then take the sealed bag with the slide mailers and
desiccant out and leave it on the counter top at rt for 15-30 min. before
opening the bag.  This allows the slides to come to rt without liquid melt
forming on the section.  You could do the same thing with say using a 100
slot slide box, a plastic bag big enough to hold a rack, in the freezer take
out the slides you need for staining, put them in the rack inside the cold
plastic bag with some desiccant, seal it up before removing from the freezer
and allow to come to rt temp without opening the bag for 15-30 min.

How well your IHC staining is after all the kinds of storage and handling
you mentioned depends individually on the target of interest.  Some targets
are hardy and will be fine, while others will be easily destroyed, you need
to choose a handling method that will assure the preservation of the weakest
target and then you can be sure they are all preserved.



Patsy Ruegg, HT(ASCP)QIHC
12635 Montview Blvd. Ste.215
Aurora, CO 80045
fax 720-859-4110

-----Original Message-----
From: histonet-bounces <@t>
[mailto:histonet-bounces <@t>] On Behalf Of Jeffrey
Sent: Friday, July 09, 2010 3:22 PM
To: histonet <@t>
Subject: SPAM-LOW: [Histonet] air dry or heat dry

We have an ongoing debate in our lab regarding the relative virtue of heat
drying slides vs RT air drying them.
Tissues: 4% paraformaldehyde perfused rat brains frozen in OCT blocks
Sections: 10 microns on a cryostat (at approx -25 C)
Slides: Superfrost Plus
The slides are stored in slide boxes at -80 C until staining.
When staining the heat dry faction (wanting to avoid icy slides) put their
slide boxes straight out of the freezeer into a 50 C oven for 30 minutes
before taking out slides to stain. then the box goes back to the freezer
until the next round of staining, 

The air dry group feels that cooking the antigens repeatedly at 50 C is
problematic so they take the frosty slides out their slide boxes and return
them ASAP to the freezer. The slides to be stained are air dried in the fume
hood for about 30 min.
A third, middle of the road, person takes her slides out of the cold boxes
and then puts the slides in a 60 C oven for 30 minutes.
For all three groups then, the slides are given a PAP pen border to prepare
for IHC and when the pen solution is dry, 10 minutes in acetone and the
remainder of the staining procedure.
So my question is: Who is using the best technique? 
Another hotly debated topic is wether it is advisable to put a drop of PBS
on the slide before 'sticking' the section to prevent folds in the
Any opinions are appreciated.
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