Lipidic phases, containing 'lipidic particles' (cardiolipin/egg lecithin in the presence of Ca2+ and egg lecithin/dioleoylphosphatidylcholine/cholesterol) have been investigated with an alternative thin-section method, using rapid cryofixation and freeze substitution according to Müller et al. (Müller, M., Marti, T. and Kriz, S. (1980) in Proc. 7th Eur. Congr. on Electron Microscopy (Brederoo, P. and De Priester, W., eds.), pp. 720-721) in combination with low temperature embedding in Lowicryl HM20 according to Humbel et al. (Humbel, B. and Müller M. (1984) in Proc. 8th Eur. Congr. on Electron Microscopy (Csanady, P., Röhlich, P.; Szabo D., eds.), pp. 1789-1798). With this method one can visualize a honeycomb structure with local fusion (joining) points between bilayers which is compatible with the structures hypothesized for lipidic particle-containing systems.