I have had this experience with some antobodies that I have worked up also.
My preference is to work up the antibody with slides cut and dried
overnoght. If there is a project that requires holding slides longer I would
do sections on slides dried overnight, slides held fo a period of time at RT
and also slides held for the same period of time at -80C. Just my opinion. 

Cynthia Favara

-----Original Message-----
From: Michelle Mcanulty-Smith - NeuronZ Ltd.
[mailto:Michelle.Mcanulty-Smith@neuronz.com]
Sent: Wednesday, April 17, 2002 11:59 PM
To: 'Lorraine Rolston'; natalya karp
Cc: histonet@pathology.swmed.edu
Subject: RE: sections storage (2)


Hi Natalya and fellow histonetters!,
This is an interesting issue as I have experienced trouble with TUNEL
staining in tissues that were already cut i.e. older unstained slides. The
tissue was human placenta and we had no staining at all but when extra
sections were cut from the same block and the process repeated we got
excellent results! and no, nothing was different and we even tried both old
and newly cut slides at the same time with the same results!)
Our blocks and unstained slides are stored in appropriate boxes at room
temperature and my understanding was the same as Lorraine's that all
cellular activity is arrested after fixation.
Sorry to have been of no particular help but perhaps of interest.
Regards
Michelle
NeuronZ Ltd
Auckland
New Zealand.

Hi Natalya,
For what it's worth,my understanding is that once tissue is sufficiently
fixed all cellular activity should have been arrested and thereafter
changes are caused by subsequent processing i.e.shrinkage,therefore once
the tissue has been sucessfully embedded into wax it is safe to store
them almost indefinitely (I don't know about countries with extreme
temperatures) at room temperature.I am quite prepared to be corrected if
I am wrong about this.Also, I believe that it is quite safe to store the
slides already cut from wax blocks.
Hope this helps!
Cheers,Lorraine.
Histology/Anatomy/Biomedical Sciences Division/Uni.of Akld./N.Z.

natalya karp wrote:

> Dear Histonetters,
>
> (I posted the below message before, but I got no
> responses (probably of the timing was wrong), so I'm
> trying again.)
>
> I have been doing TUNEL staining on Peyer's patches of
> the small intestine and spleen. Tissues are derived
> form mice treated with a cytotoxic drug, with the
> purpose of evaluation of apoptosis as a marker of the
> drug's toxicity.
>
> My questions are:
> 1)What are the rules for the storage of paraffin
> blocks?  Should the blocks be stored in the
> refrigerator or at the room temperature?
> 2)For how long the sections can be stored at the room
> temperature before the staining?
> 3)If the sections are stored at the room temperature
> for several month, could one expect the increase in
> the number of apoptotic cells due to spontaneous DNA
> degradation?
>
> Any comments and responses will be greatly
> appreciated.
>
> Natalya Karp, M.D.
> McGill University, Dept. of Human Genetics
> Montreal, Quebec, Canada
>
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