Chick embryo fibroblasts (CEFs) spontaneously form multicellular and multilayered sheets suspended on the network of glass fibres which are stabilized by fibronectin containing protein deposits located at cell-to-cell contacts. The cells situated within the sheets are surrounded by the neighbouring cells and their mechanical equilibrium is stabilised by intercellular ?parabaric? effects. It was found that CEFs in the sheets retain relatively high mitotic activity corresponding to that observed in sparse monolayer cultures. These cells grew up to much higher local density than in confluent and contact-inhibited monolayer cultures and developed an abundance of microfilament bundles that terminated at vinculin-containing protein complexes. The results presented demonstrate that direct contact with solid substratum, cell-to-cell contacts, local cell density, and intercellular exchange of humoral factors are not directly involved in the density-dependent inhibition of growth observed in monolayer cultures. They also support the concepts concerning the role of mechanical equilibrium of cell membrane and sub-membranous cytoskeleton in the regulation of proliferation of non-transformed cells.