Extraction of lipids from tissue sections with acetone: further qualitative and quantitative histochemical observations

Synopsis Human atherosclerotic intima, aortic media and cerebral white matter were stained by a variety of histochemical phospholipid methods. Preliminary acetone extraction prevented all the subsequent phospholipid reactions in the fixed atherosclerotic intima, except the scanty reaction with Nile Blue sulphate. Such extraction did not significantly alter the staining of fixed aortic tunica media or myelin with the osmium tetroxide--naphthylamine, Nile Blue sulphate and ultraviolet-Schiff methods. The slight staining of the tunica media with acid Haematein and gold-hydroxamic acid was extinguished by acetone extraction, but the reaction of myelin with these two methods was not convincingly reduced.Acetone followed by aqueous extraction removed over half of the phospholipid from unfixed or briefly-fixed atherosclerotic intima, as shown by quantitative histochemical thinlayer chromatography. Such extraction removed only a small amount of phospholipid from unfixed or briefly-fixed histochromatographic preparations of white matter; the aortic media was intermediate in this respect between the atherosclerotic intima and cerebral white matter. Fixation with calcium-formalin for periods of 3 days and over, preserved 80% or more of the phospholipids in all the tissues examined, and is recommended when tissue lipids are tested for their acetone solubility. The anomalous extinction of histochemical phospholipid reactions in long-fixed atherosclerotic intima by acetone cannot be explained by these chromatographic results.Research Associate by the Wellcome Trust.