Application of freeze-etching to the study of myogenesis in cell culture

Abstract A method is described for in situ freeze-etching of cells grown in monolayer culture, with preservation of delicate surface structures such as filopodia. The close intercellular contact which is a prerequisite for fusion of myogenic cells appears to depend on and be mediated by filopodial contacts: cells grown in standard fusion-permitting medium show frequent filopodial contacts, whereas cells in medium depleted of Ca 2 ions by the addition of EGTA lack filopodia and fail to fuse.