Jamie,

Using dry ice mixed with isopentane or hexane will work just as well for 
snap freezing (i.e. cryopreservation?) as liquid nitrogen/isopentane.

The problem with liquid nitrogen and isopentane is the constant recooling 
of the isopentane to the correct temperature when snap freezing a large 
number of tissues during a long freezing session   We gave up on this 
method years ago and opted for dry ice/isopentane or hexane slurry.  You 
can also use a petri dish floating in liquid nitrogen, that way you can 
snap freeze multiple samples rapidly, and get rid of isopentane, always a 
storage dilemma unless you have explosion proof freezers/refrigerators.  We 
often snap freeze 30 blocks during a dissection/snap freezing session.  We 
also had our OCT crack in the liq N2/isopentane method, it was just too cold.

I will be happy to send you a powerpoint showing how this is done (both 
methods).  We do not have freezing artifact.

For LCM, a colleague and expert at doing this, snap freezes tissues in dry 
ice cooled hexane but does NOT put the dry ice into the solvent, she merely 
surrounds the beaker of hexane with dry ice until correct temperature is 
needed.  You can discuss this with her via email privately, I will send her 
email address to you privately if you want it.   She does work with rodent 
tissues.

No papers, just experience and learning the hard way for our 
laboratory.  MyNeuroLab website has a discussion or at least Charles 
Scouten on the theory of snap freezing.



At 09:03 AM 5/11/2006, you wrote:
>Hello histonetters,
>                                       I am hoping that someone out there
>can help me with a cryopreservation dilemma. I am in a research pathology
>lab and we have two schools of cryopreservation here, some researchers use
>dry ice isopentane and others use liquid nitrogen isopentane. I have heard
>that LN2 is faster with less ice crystal  formation  and I think this is a
>better way to freeze but I need to convince the dry ice people to use LN2.
>Does anyone have papers that will support my fight for one standard way of
>freezing. Any thoughts or help with literature would be great. We freezing
>mouse and rat  tissues for IHC and LCM (laser capture microdissection ).
>
>Thanks
>
>
>_______________________________
>Jamie Erickson
>Sr. Research Associate
>Department: DSMP
>Abbott Bioresearch Center
>100 Research Drive
>Worcester, MA 01605-4341
>508-688-3134
>FAX: 508-793-4895
>e-mail: jamie.erickson@abbott.com
>
>_______________________________________________
>Histonet mailing list
>Histonet@lists.utsouthwestern.edu
>http://lists.utsouthwestern.edu/mailman/listinfo/histonet

Gayle Callis
MT,HT,HTL(ASCP)
Research Histopathology Supervisor
Veterinary Molecular Biology
Montana State University - Bozeman
PO Box 173610
Bozeman MT 59717-3610
406 994-6367
406 994-4303 (FAX)



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