“…Light microscopic observations of structural changes in living cells under aldehyde treatment have shown that many organelles, such as mitochondria (Bereiter-Hahn and Voeth, 1979), chromosomes (Skaer and Whytock, 1976), or cytoskeletal elements (Luther and Bloch, 1989) undergo significant changes in shape or position in the early seconds of fixation, before gelation of cytoplasm (Millonig and Marzzoni, 1968). Furthermore, as aldehydes cannot effectively cross-link membrane-lipids, membrane artefacts are often observed (Baker, 1968;Bereiter-Hahn and Voeth, 1979;Hasty and Hay, 1978). Fixation-induced fusion of vesicles has been observed (Bretscher and Whytock, 1977;Doggenweiler and Heuser, 1967;Hausmann, 1977).…”