Re: CryoJane & Gentle Jane

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From:Philip Oshel <>
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I have to take issue with a piece of this post. The description of 
what the "Gentle Jane" is doing in terms of freezing cannot be 
correct. In order to form vitreous ice, or the microcrystalline ice 
that many folks call "vitreous", freezing rates must exceed 10,000 
deg. C per second, and even at that rate, only the outmost 500 
microns (at best) of a sample will be "vitreous". This is of a very 
small sample of maybe 1 cubic millimeter or so. Larger than that, and 
the sample retains enough heat that the
10,000 deg/sec freezing rate will not be obtained as deeply as 500 
microns. Also, this is only possible in a high-pressure freezer where 
the sample is frozen at around 2100 barrs pressure. Less than this 
and only 100 or so microns of sample will have "vitreous" ice. The 
increased pressure coupled with the rapid freezing forces the ice to 
take on a cubic crystal structure instead of its more familiar 
hexagonal structure, or the pressure prevents formation of a 
crystalline lattice at all (the major reason for this is that the 
hexagonal crystal structure takes up more volume than the cubic or 
"vitreous" phases, and the high pressure prevents this volume 

Freezing by simple contact for 8-10 seconds at standard pressure at 
any temperature cannot result in vitreous ice or even cubic ice. It 
may very well form smaller or much smaller than normal ice crystals, 
and the damage caused by these crystals may well be below the 
resolution of the light microscope (as normally used, anyway), but 
the sample will be full of nice, hexagonal ice. So, the sample will 
have all the dehydration and mechanical damage caused by the 
formation of this ice, just not at a light microscopic level (one 

(Grunt running the High-Pressure Freezer and cryo-FESEM.)

>Hi Histonetters,
>All the  "Janes" are confusing!  Clarification!
>The Gentle Jane (Stand Alone Gentle Jane) is a snap freezing system. A
>weighty heat extractor is chilled (preferable in liquid nitrogen) and then
>it is hung on the device. It drops at a controlled rate and gently contacts
>the 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!
>The CryoJane Tape-Transfer  system is installed in the cryostat. The section
>is cut onto a cold tape and transferred to a cold slide inside the cryostat.
>The section stays frozen until the section is fixed, freeze-substituted or
>air-dried. This process produces paraffin-quality frozens that are thin,
>flat and intact. Yes, and you cut fat, bone etc.with little sweat!

Philip Oshel
Supervisor, AMFSC and BBPIC
Dept. of Animal Health and Biomedical Sciences
University of Wisconsin
1656 Linden Drive
Madison,  WI  53706-1581
voice: (608) 263-4162
fax: (608) 262-7420 (dept. fax)

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