Modulation of the effect of colchicine and cytochalasin b on fibroblast aggregates by the substratum

In previous investigations, we have shown that aggregates of normal human fibroblasts displayed a remarkable number of morphogenetic properties in suspension and on a substratum. The present investigation has attempted to illustrate more clearly the role of colchicine- and cytochalasin-sensitive structures in the observed ultrastructural properties of the fibroblasts in this system. Cytochalasin B and colchicine alter the surface ultrastructure of the cells as well as the behaviour of the cells during aggregate outgrowth. In addition, the effects of both drugs on the cells in the aggregates are modulated by the attachment of the aggregates to a substratum.