SPECIAL FEATURES OF PHOSPHATIDYLCHOLINE VESICLES AS SEEN IN CRYO-TRANSMISSION ELECTRON-MICROSCOPY

Vesicles of egg yolk phosphatidylcholine (EYPC) were studied by cryo-t ransmission electron microscopy. The electron micrographs indicate tha t, despite the rapidity of cooling, membrane undulations are flattened and some vesicles change their shapes before the samples freeze. Thes e artefacts are attributed to the action of the lateral tension that r esults from the membrane area contraction associated with the temperat ure drop. Other micrographs represent grainy membranes and angular ves icles. We regard them as the first direct evidence for the superstruct ure and optically invisible roughness which were recently postulated f or these membranes.