Hi all,
Just to add my insights to this discussion:
Of course quick freezing using cooled isopentane is the most preferred 
method. But we have been freezing heart biopsies and atherectomy specimens 
with dry-ice successfully. The biopsy was immersed in one drop of OCT at 
the bottom of an aluminium tissue storage can (3x3 cm). The bottom of this 
can was hold against some dry-ice pellets for "quick" freezing. However, 
incidentally we have also placed the alu storage can with OCT emerged 
biopsy in a -80 freezer. That also worked well. Morphology and 
immunostaining were good.

Chris van der Loos
Dept. of Cardiovascular Pathology
Academical Medical Center
Amsterdam - The Netherlands

 >Date: 3 Jun 2003 17:16:14 -0500
 >From: Gayle Callis 
 >Subject: More on kidney frozen sections
 >
 >- -70C is still not cold enough, putting the biopsy into a -70C freezer is
 >not SNAP freezing, nothing will change in terms of section quality.
 >
 >I forget to mentioned that we cut 4um frozen sections.And as liquid nitrogen
 >is not very convenient for the technician in our routine work.I just wonder
 >if we could put the OCT-specimen in a -70C fridge for quick freezing?
 >
 >And could I do as below,
 >Fix the fresh specimen in a kind of fixation solution first(like ethanol)
 >and then transfer it to the lab at 4C.
 >Immerse the specimen in OCT on a metal holder.
 >Put them all in -70C immediately.
 >After OCT is frozen,transfer them quickly into the cyrostat which adjust to
 >- -18C and then sectioning.
 >Gayle Callis
 >MT,HT,HTL(ASCP)
 >Research Histopathology Supervisor
 >Veterinary Molecular Biology - Marsh Lab
 >Montana State University - Bozeman
 >S. 19th and Lincoln St
 >Bozeman MT 59717-3610

406 994-6367 (lab with voice mail)
406 994-4303 (FAX)

email: gcallis@montana.edu