[Histonet] RE: Histonet Digest, Vol 95, Issue 16 Drying Oven temps

[Steve McClain]

It is important to clarify the terminology-what you  mean by 'drying' oven?
The remarks below refer to the manual step of annealing unstained sections on slides prior to de-paraffinization and staining.

The point or objection to the terminology of 'drying' oven relates to a far too common practice of wet slides on a slide warmer or in the 'drying' oven immediately which is visibly injurious to the tissue section, 
resulting in loss of contrast between H and E,
leading to antigen loss and inconsistent IHC staining.
In my opinion, this is an absolute NO.  
NO wet slides on a warmer or in a 'drying' oven unless you desire to prepare miniature protein 'soup' with purple staining rather than distinct red and blue staining.
We stand slides upright along the slide warmer on a towel until visibly dry and shake-off the few remaining drops at the slide bottom edge before warming for a period, racking, and then proceeding to the annealing oven.

Routinely for skin we anneal ('bake" is another commonly used yet imprecise term) 
racked previously dried slides for 20 min at 65-70 C for most stains.
IHC slides can be annealed overnight at 60 C with good results.  
For a same day IHC case cut in the morning 60 minutes at 65-70 C for shaves and punch biopsies suffices, while 120 minutes improves excisions and large samples.
	(Note: These times may seem long, but it depends on the tissue and to some degree size of the sections, and the antigen retrieval method. 
	 Bear in mind for skin, preserving cornified layer, epidermis, dermal collagen, and SQ adipose tissue on the slide through heat antigen retrieval is a challenge.) 
For nails and hooves 80 C for 60 minutes suffices for PAS, PASD and GMS stains.

Those with other special tissue experience, e.g., brain, skeletal muscle, bone, please speak up.
I hope those with experience in more automated labs can speak to the temperatures in automated stainers and automated IHC having their own ovens.

Finally, I hope someone with experience in in-situ PCR can speak to the needs of their procedure.

Steve A. McClain, MD
631 361 4000


Message: 5
Date: Tue, 11 Oct 2011 20:36:20 +0200
From: "V. Neubert" <histonet.nospam <@t> vneubert.com>
Subject: Re: [Histonet] Drying oven temps
To: histonet <@t> lists.utsouthwestern.edu
Message-ID: <4E948CA4.2050702 <@t> vneubert.com>
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59 °C, 1h, for all slides.

> Is anyone willing to share their slide drying temperature and times?  Does anyone know of a particular standard concerning this?
>
> Kimberly Artim, AST, HT (ASCP)
> Technical Coordinator, Anatomic Pathology
> St Lukes Hospital & Health Network
> 801 Ostrum Street
> Bethlehem, PA 18015
> 610-954-4832