[Histonet] Postive charge slides, section loss and drying

[Morken, Tim - Labvision]

Ah, the lore of histology

" When you room temperature dry the slides, the water will dry from the
outside in.  Once the water is out from the edge of the slide, the paraffin
sort of adheres itself to the slide around the tissue, creating a seal that
doesn't allow any more water to escape from under the paraffin."

" We keep a razor blade handy to release water blebs at section edge before
racking up and drying."

"Vertical draining of slides in a polypropylene slide holder is important
before loading slides in horizonal position in a rack."


I'll add my technique (such as it is) to the lore of histology:

To lessen water entrapment I don't let the slide just passively drain.
After picking up a section I do a quick wicking of exess water by holding
the slide vertically on top of  a paper towel and then give the slide  a
quick " wrist snap"  to force out water from under the section (Think of
snapping a whip - it's all in the wrist action!). I'm careful about fragile
tissue and haven't had any problems with tissue damage doing that. It seems
to get rid of most of the water under the section. If the section is
especially fragile I just do the wicking, but do it on the short and long
edges of the slide.  

Tim Morken


-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Gayle Callis
Sent: Friday, December 10, 2004 9:54 AM
To: Histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] Postive charge slides, section loss and drying 



>
>Jeff,
>
>It was pointed out to us (by Marcia  (sp?) from Newcomer Supply) - it 
>is
>important  HOW a section is picked up.  One should make sure the tissue 
>portion of paraffin section comes into contact with positive charged 
>surface very quickly during picking up motion.  This permits the tissue to 
>adhere better, without so much water underneath it,  onto the positive 
>charged surface. IF the section is in good contact with the slide, there 
>will be better interaction of plus charge to tissue,  and you would not 
>have to depend so much on paraffin melting to allow water to escape under 
>this + / - seal.
>Vertical draining os sllides in a polypropylene slide holder is important 
>before loading slides in horizonal position in a rack.  We keep a razor 
>blade handy to release water blebs at section edge before racking up and 
>drying.  We have actually dried sections on Plus charge slides for 1 hour 
>at 60C and still had water present under paraffin.  This ceased after 
>tweaking picking up technic and vertical drying.
>
>At 09:53 PM 12/9/2004, you wrote:
>
>>1)  Drying (most common).  When you room temperature dry the slides, 
>>the
>>water will dry from the outside in.  Once the water is out from the edge 
>>of the slide, the paraffin sort of adheres itself to the slide around the 
>>tissue, creating a seal that doesn't allow any more water to escape from 
>>under the paraffin.  It can sit there for a month and still have water 
>>trapped under the tissue in this condition.  When you put the slides in 
>>the oven, the paraffin melts allowing water to escape from under the seal 
>>and under the tissue, thereby allowing the tissue to fully adhere to the 
>>slide without any water barrier separating any part of it.

Gayle Callis
MT,HT,HTL(ASCP)
Research Histopathology Supervisor
Veterinary Molecular Biology
Montana State University - Bozeman
PO Box 173610
Bozeman MT 59717-3610
406 994-6367 (lab with voice mail)
406 994-4303 (FAX)



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