THE ACTION OF FORMALDEHYDE SOLUTIONS ON HUMAN BRAIN LIPIDS

Abstract

The composition of the lipids extracted from fresh normal human brain and from brains preserved up to 24 years in unbuffered formaldehyde solutions was analysed quantitatively using column and paper chromatography, followed by various determinations. The amounts of cholesterol, cerebrosides, sulphatides, phosphoinositides and sphingomyelin remain unaffected. Lecithin, phosphatidylethanolamine and phosphatidylserine are broken down to the corresponding lyso compounds, fatty acids, phosphatidic acid and probably lysophosphatidic acid. The lyso compounds are further broken down by the liberation of the second fatty acid. By this process the fatty acid content is markedly increased. The total lipid content decreases slightly by the formation of water soluble phosphoryl compounds. Consequently the phosphorus content of the total lipid extract suffers marked diminution. Histochemical reactions on lipids in formaldehyde stored tissues should preferably be performed in combination with an analysis of the lipid extract.