Determination of lipid loss during aqueous and phase partition fixation using formalin and glutaraldehyde.

Phase partition fixation permits fixation of tissue in a nonaqueous environment, thus eliminating osmotic effects. It was shown in an earlier investigation that retention of protein in liver blocks can be improved by phase partition fixation. By using radioisotopic labeling techniques, the effects of phase partition fixation on lipid retention during fixation, dehydration, and clearing have been determined and compared with those of standard aqueous fixation techniques. In this article we show that retention of total lipid in liver blocks following phase partition fixation using formalin was comparable to or better than that with aqueous formalin fixation and processing. Fixation with glutaraldehyde using phase partition fixation resulted in somewhat greater loss of total lipid than that observed for aqueous buffered glutaraldehyde-fixed blocks.