Dear Tamara,
Simple snap freezing of most tissue specimens can be done as follows:
We use little aluminium cans with screw cap for tissue storage at -80C (29 
mm diameter). Those cans can also be used for freezing. First we put one 
drop of OCT compound inside the can at the bottom, then put the tissue in 
it. If the tissue is a small biopsy it is totally immersed in OCT compound. 
Pick up the can with forceps and touch the surface of the liquid nitrogen 
with just the bottom of the can. Do not let the liquid nitrogen come into 
the can. Consequently, the tissue specimen will break up!

Chris van der Loos
Academic Medical Center
Amsterdam, The Netherlands

Tamara wrote:
 >From: Tamara Howard [mailto:thoward@unm.edu]
 >Sent: Friday, January 17, 2003 3:36 PM
 >To: HistoNet; Microscopy Server
 >Subject: LM: freezing tissue - method?
 >I'm sort of conducting a survey - how do you freeze blocks prior to
 >cryostat sectioning? A PI in our department is writing a grant and
 >offered
 >to include a freezing set-up (we just use a dewar of LN2 now) - the only
 >equipment I've come across on the web is the giant NesLab bath. Is a
 >styrofoam cooler of LN2 with a beaker of some solvent still a reasonable
 >way to go, or is there some spiffy gizmo we can buy?
 >Thanks! (Sorry about the cross-post for those of you on both lists)
 >Tamara
 >
 >Tamara Howard
 >Department of Cell Biology and Physiology
 >University of New Mexico - Health Sciences Center
 >Albuquerque, NM 87131