X-Message-Number: 15273
Date: Sat, 6 Jan 2001 10:39:28 -0800 (PST)
From: Doug Skrecky <>
Subject: chemical fixation

> Message #15268 From: Charles Platt <>
> 
> I recall that the chemical
> fixation creates such rigid bonds, when refrigeration adds its mechanical
> stresses, the eventual breakdown of the system is more chaotic. Like
> bending a substance that is brittle and shatters, as opposed to bending a
> substance that retains some malleability.
>
 I have examined the effect of refrigeration on chemical fixed tissue in
the medical literature. Contrary to your assumption, this has been found
to be highly beneficial. For example DNA deterioration in formaldehyde
embalmed material is significant at room temperature, but is negligible
over a week at 4 C. Adding salt also helps stabilize DNA.
 Frozen fixed tissue may exhibit increased intracellular ice crystal
disruption, due to cell membranes being made too permeable, to
allow freeze concentration mediated dehydration of cells.
 Although I agree that fixation in combination with liquid storage is
not adequate to insure excellent preservation of tissue over long periods,
tissue morphology can be excellent over short time frames. At present the
only possible alternative to cryonic storage is mummification. This is
also the only option if very long periods of storage (>1000 years) are
contemplated.

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