During development, groups of cells coordinate their behaviour to generate functional tissues. For this, a range of communication mechanisms determines when and where different cellular responses take place. Signalling pathways have been well characterised at the intracellular level. However, to get a global understanding of cell-cell communication and its spatiotemporal control, it is important to take into account where signals emerge from and at the same time, how a behaviour of a tissue is influenced by other tissues.