Re: [Histonet] H&E to PAS restaining protocol

From:John Kiernan

Russ Kerschmann MD wrote:
> Can anyone provide a protocol for reprocessing an H&E
> slide into a PAS slide?  Can the reverse also be
> performed?  

Easy! Here's a procedure. I'm not happy about
calling this kind of thing a "protocol" because
it needs observation and judgement if it's to
work properly. You should do this job yourself;
do not entrust it to someone else.

1. Remove the coverslip and mountant and 
   take the section to 70% alcohol. Don't 
   rush any step of this procedure, and be
   especially certain that you have
   dissolved out all the mounting medium.
2. Immerse in acid-alcohol until all the
   haemalum nuclear (and any other blue)
   staining has gone.
3. Rinse in 70% alcohol, then in water.
4. Put in slightly alkaline water until
   the eosin colour (pink) has all gone.
     (Note. You will probably not be able
   to extract eosin from a few strongly
   basic materials present in some animal
   tissues: eosinophils, Paneth cells and
5. Wash in tap water, then in distilled
   water before doing the PAS method.

>How can the risk of losing the tissue be
> minimized?

Keep exposure to alkalinity (Step 4 above)
to a minimum. Hard tap water may be 
sufficient, or you can add a small drop of 
ammonium hydroxide, or of saturated aqueous 
lithium carbonate. High pH removes sections
from slides.
> Many thanks, and Happy Holidays.

Which holiday(s)? The next one on my calendar is
Nobel Day (Sweden) on 10th December, followed by
Our Lady of Guadalupe (Mexico & Central America)
2 days later. Chanukah isn't until the 19th.
Or do you mean happy Christmas? It's still
25 days away!

Hope this helps.
John A. Kiernan MB, ChB
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1

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