Fig. 1. Morphological transitions in Dictyostelium development. Dictyostelium development is characterized by a series of coordinated changes. The process is highly synchronous as most of the multicellular structures are at the same morphological stage at each time point (Sussman, 1987). A top view of cells developing on dark nitrocellulose filters is shown. No multicellular structures can be seen at 0 hours. Ripples (6 hours), loose aggregates (10 hours), tipped aggregates (14 hours), fingers (18 hours) and fruiting bodies (24 hours) are shown. Time (h) is indicated in each panel. Bar, 1 mm.