| Abstract: | The effect of cytochalasins B or D on the surface topography of mouse neoplastic fibroblasts of L line (detached from glass by trypsin-EDTA solution) or of its LS subline (adapted to the growth in suspension in vitro), as well as on that of Ehrlich's ascites tumor cells was investigated by screening electron microscopy. Incubation of suspended cells with cytochalasin B (2 micrograms/ml) or cytochalasin D (0.2 microgram/ml) for 30-180 min led to the following changes: (I) progressive decrease of the proportion of the cells with a microvillous surface relief and simultaneous increase in the percentage of the cells with a blebbed microrelief; (2) shortening of the microvilli and decrease of their density on the cell surface; (3) appearance of surface areas with a rough folded relief; (4) formation of very large blebs on the LS or L cell surfaces; (5) unusual "polar" distribution of blebs on Ehrlich's tumor and L cells: the blebs were concentrated in one locus on the cell surface. The data show that normal organization of the actin microfilament system in the cell cortex is necessary for formation of the microvilli but not for the blebs. |
