[Histonet] Flash-freezing samples in OCT?

Constance McManus ladylaynah <@t> yahoo.com
Sun Jul 8 17:39:41 CDT 2007

I have been doing IHC on frozen sections and one thing I can tell you --- and I stress this point emphatically --- do not thaw the tissues, then freeze them again and try to do IHC on them.  This causes the cells to lyse which in turn will destroy epitopes.  Keep the tissue frozen.  I would section them as they came.  

Connie McManus, HT
Univerisity of Utah
School of Medicine
Dept of Dermatology

----- Original Message ----
From: Mariano S. Viapiano <msviapiano <@t> yahoo.com>
To: histonet <@t> lists.utsouthwestern.edu
Sent: Friday, July 6, 2007 4:40:10 PM
Subject: [Histonet] Flash-freezing samples in OCT?

Hi everyone, 
We just received some frozen brain tumor samples to
process for IHC but are a bit confused about how they
were prepared. We fix our samples in 4% PFA, change
them to 30% sucrose until they sink, embed in OCT and
freeze them at -80C until cryostat sectioning. On the
other hand, the samples we received were fresh
specimens (just out of the OR) dipped in OCT and
snap-frozen in liquid nitrogen. What would be the best
thing to do? Section them as they came, or thaw them,
remove the OCT and do our fixation procedure before
sectioning? I am a bit concerned about the OCT having
acted as a “retardant” for the snap-freezing of those
samples when they were submerged in nitrogen (or am I
just imagining things?)
Thank you!

Mariano S. Viapiano, PhD
Assistant Professor
Center for Molecular Neurobiology and
Department of Neurological Surgery
The Ohio State University
226B Rightmire Hall
1060 Carmack Rd., Columbus OH 43210
Tel (614) 292-4362
Fax (614) 292-5379

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