Three-dimensional identification of actin filaments in phalloidin-treated rat livers by quick-freezing and deep-etching method.

An increase in microfilaments in phalloidin-treated hepatocytes of Wistar rats was identified three-dimensionally with myosin subfragment 1 (S1) on replica membranes, using the quick-freezing and deep-etching method. Almost all of the reticular microfilaments around the bile canaliculi and beneath the lateral cell membranes were decorated on their surfaces by S1 attachment. Some showed periodic structures. However, thinner filaments with diameters of 4-7 nm were not decorated by S1. Bundled intermediate filaments around the bile canalicular microfilaments and intermediate filaments localized among cell organelles had smooth surfaces without S1 decoration. The microfilaments decorated by S1 were attached directly to bundled intermediate filaments. The quick-freezing and deep-etching method is useful in analysing cytoskeletal pathology and can be applied to histochemical fields.