(a) Schematic of repressive interactions via Notch-Delta between neighbouring cells whereby the effects of HES5 protein in Cell 1 (marked as P1) on transcription in Cell 2 and vice-versa are represented using an inter-cellular Hill function J(P1, 2(t−τND)) where t denotes time and τND represents the intercellular time delay, the time interval required to synthesise the intermediate molecular species (detailed in Figure EV4a); HES5 auto-repression is represented using an intra-cellular Hill function G(P1, 2(t−τH)) where τH represents the inter-cellular time delay, the time interval required for protein to be produced and repress its own transcription. 