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. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=15273