On Tue, 4 Apr 2000, Instrumedics, Inc. wrote:

> All the  "Janes" are confusing!  Clarification!
> 
> ... tissue and CryoGel or other embedding medium. The block is frozen in
> 8-10 seconds. The temperature of the heat extractor,-196deg. C, and the
> thermal exchange derived from its highly polished chrome finish, produces
> "amorphous" ice rather than "crystalline" ice. minimizing ice crystal
> artifact. The morphology of the tissue is preserved!

  You aren't going to get amorphous (i.e. vitreous) solid water by
  this method, especially if it takes 8 seconds to freeze the
  middle of the block, though the ice crystals may be too small
  to make visible holes in the tissue. For vitrification you need
  liquid helium temperature. See Bald, WB (1983) Optimizing the
  cooling block for the quick freeze method. J Microsc 131: 11-23;
  also Chapters 2 & 3 in Pearse's "Histochemistry," 4th edn, Vol 1.

 John A. Kiernan,
 Department of Anatomy & Cell Biology,
 The University of Western Ontario,
 LONDON,  Canada  N6A 5C1