THE CYTOSKELETON OF SPREADING DICTYOSTELIUM AMEBAS

The cytoarchitectural elements of Dictyostelium discoideum amoeba have been visualized by light and electron microscopy in cells prepared with mixtures of glutaraldehyde and Triton-X-100. After negative staining, the peripheral regions of spreading amoebae show a complex meshwork of actin filaments, the majority of which were less than 0.25 microns in length. Multiple branch points, end to side abutments and cross-overs were characteristic features of the actin meshworks. Filopodia extending from the cell periphery consisted of bundles of actin filaments that penetrated into and merged with the actin meshworks in the spreading lamellae. Microtubules emanating from the nucleus associated body penetrated to differing extents into the actin meshworks, sometimes extending close to the cell periphery. Dictyostelium cytoskeletons prepared as described here should prove useful for further studies on the locomotory mechanism.