X-Message-Number: 1425
Date: Fri, 11 Dec 92 23:17:54 CST
From: Brian Wowk <>
Subject: CRYONICS: freezing damage

        It is good to see a discussion of freezing damage underway on 
the net, and that this discussion is frank.  Mike Darwin's brutal 
account of the damage done by current cryopreservation techniques serves 
as a strong argument for developing better ones.  However Jeffrey 
Soreff's recent question about the possible superiority of chemical 
preservation over cryopreservation suggests that undue pessimism has 
been generated.
 
        According to a presentation made by Greg Fahy at the Alcor 
Anniversary Dinner earlier this year, the breaks produced by growing ice 
crystals are "clean" on an ultrastructural level.  In other words, the 
broken edges are smooth, not frayed, when viewed on (freeze-substituted) 
electron micrographs.  Additionally the broken bits are moved only 
microns, not off to parts unknown.  Yes a frozen brain is a jigsaw 
puzzle; one with many disconnected pieces lying very close to where they 
ought to be, not one with badly jumbled or missing pieces.  I, for one, 
am far from convinced that neural connectivity information is 
irreversibly lost in brains frozen with current (or even past) methods.
 
        It is important to keep information, both positive and negative, 
in perspective.  On the positive side, it must be remembered that 
cryoprotected freezing is the only current means of maintaining the 
*functional viability* of individual brain cells indefinitely.  It must 
also be remembered that freezing tends to *move things around*, not 
outright obliterate them (which is what chemical preservation does to 
 all but the grossest level of neural anatomy).  Freezing is not so bad 
 that we need to look at entirely new modalities.  As Mike says, what we 
 need to do is make freezing even better by following promising leads on 
 ways to reduce and eliminate ice formation.
 
                                                 --- Brian Wowk

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