The effect of cytochalasin B on chick mesoderm cells as studied by scanning electron microscopy.

The effects of cytochalasin B (CCB) on chick mesoderm cells in vivo was examined by scanning electron microscopy (SEM). The embryos were mounted for New Culture and the mesoderm exposed by dissecting off the endoderm. Cytochalasin B was suspended in saline and the embryos flooded with the suspension. Control embryos were treated with saline alone. The embryos were reincubated for varying times at 37 degrees C. In the treated embryos the mesoderm cells were rounded and separated from each other. Many had long branched processes and rough surfaces. These changes became more pronounced as treatment time was increased. They were also reversible on reincubating treated embryos in the absence of cytochalasin B. The morphological changes produced by CCB are thought to be due to an effect on the cytoskeleton, either a direct disruptive effect or detachment of skeletal microfilaments from the cell membrane. There may also be a direct removal of cell surface materials leading to the observed surface roughening of treated cells.