[Histonet] O.C.T. embedding vs. freezing of unembedded

[Amos Brooks]

Mareike,
     When you freeze the tissue without the OCT, you will eventually need to
embed the tissue in OCT to cryosection it. When you do this you are putting
warm OCT on frozen tissue which then thaws the tissue out before freezing it
again. This will produce ice crystals worse than not snap freezing in the
first place. If you intend to use the tissue for something other than
cryosectioning, it will not be harmed by the OCT, however the cryosectioning
can (will) be harmed by not freezing in OCT. Also, (as an afterthought) if
there happens to be any temperature fluctuation in storage, the tissue will
have a little more protection in the OCT.

Hope this helps,
Amos Brooks

Message: 21
Date: Fri, 25 Jan 2008 11:39:00 -0000
From: "Mareike Heimann" <mareike <@t> hi.is>
Subject: [Histonet] O.C.T. embedding vs. freezing of unembedded
       samples
To: <histonet <@t> lists.utsouthwestern.edu>
Message-ID: <003401c85f46$e11b20a0$5a96d082
@MrDarcy>
Content-Type: text/plain;       charset="iso-8859-1"

Hi there,

I have been wondering about the advantages (or disadvantages) of embedding
tissue in O.C.T. before snap-freezing in liquid nitrogen when compared to
snap-freezing the "naked" tissue.
I do use O.C.T. before freezing, but when recently asked why, I found no
better answer than "it seems to be what most people do..."
I would be most grateful for any explanations!
(My tissue blocks are used for immunohistochemical stainings later on)

Regards,
Mareike