Fig. 1. Dictyostelium development. Amoebae proliferate as single cells during the growth phase. Upon starvation, amoebae undergo chemotaxis towards a pulsatile cyclic AMP (cAMP) source. During aggregation, cells coalesce into adherent cell ‘streams’ that eventually come together to form the mound, the first stage of multicellular development. The mound compacts to form a tight aggregate and then develops a ‘tip’, which coordinates further development. After extension to form the first finger, the developing structure either immediately forms a fruiting body, the process of culmination or forms a motile slug that migrates to seek conditions favourable for culmination. Scale shows relative timing of development.