X-Message-Number: 5013
Date: Wed, 18 Oct 1995 14:58:46 -0700 (PDT)
From: Doug Skrecky <>
Subject: request for help - third answer

 Suggestion #5: If alcoholic dehydration is used consider adding glycerol
 to the alcohol based substitution medium. 
     This has had a remarkable effect on preventing fat from leaching from
 tissue. (J Anat 295-297 Vol.182 1993) Adding polyethylene glycol or
 acacia gum also seem to help, but these diffuse poorly into tissue. (Am J
 Clin Pathol 620-623 Vol.88 1987 & J Microscopy 69-84 Vol.92 Pt.2 1970)
     After 24 years of storage tissue preserved in formaldehyde retained
 cholesterol, cerebrosides, sulphatides, sphingomyelin and
 phosphoinositides. Lecithin, phosphatidyethanolamine and
 phosphatidylserine are lost. (J of Histochemistry & Cytochemistry 704-709
 Vol.10 1962) This difference in stability is reflected in the results
 obtained with formaldehyde treated tissue that is subjected to a
 methanol/chloroform wash. Even with lipid stabilizers such calcium
 chloride or uranyl nitrate lecithin and phosphatidylethanolamine show
 marked losses, while sulphatides and spingomyelin cerebroside are
 retained. (Histochemical J 323-360 Vol.1 1969) Glutaraldehyde has little
 effect on retention of lipids, while osmium tetroxide while affording
 nearly complete retention diffuses poorly. (J Microscopy 1-15 Vol.133
 Pt.1 1984)

 Suggestion #6: Consider using a silica gel bead desiccant packed
 anhydrous solution of ethylene glycol and glycerol. 
     VS11 (6 M ethylene glycol, 1.8 M glycerol) has a very high glass
 forming ability. (J Reproduction & Fertility 65-70 Vol.99 1993) By
 themselves ethylene glycol, glycerol (and triethylene glycol) have been
 used to dehydrate tissue with great success. (Lab Invest 655-663 Vol.62
 No.5 1990 & J Microscopy 195-203 Vol.172 Pt.3 1993)


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