Transmission electron microscopy of biliary mixed lipid micelles

One potential artifact problem in election microscopy of micellar systems is that structural changes and aggregation could be induced by high vacuum dehydration in sample preparation prior to viewing and photomicrography. This could account for an earlier report on "macroassemblies" of biliary lipid, a finding which has been discrepant with the predominance of other evidence on the size, configuration and behavior of biliary micelles. In the present work, this possibility was explored and no evidence for such macroassemblies demonstrated when freeze-drying sample preparation was used; whereas, with conventional technique, the "macroassemblies" were again observed. It is concluded that freeze-drying or freeze-etching sample preparation is required to avoid this form of artifact in electron microscopy of micellar systems. The present findings are compatible with a spherical-equivalent or oblate ellipsoid configuration for biliary mixed micelles.