Figure 2.

Schematic of possible signalling interactions between cells in the model. Here, Notch–Delta signalling at the junctional contacts does not always lead to activation of the Notch receptor (R). Instead, the receptor (N) can bind to Delta (D) in trans without becoming activated (w_a > q_a). Interactions mediated through the protrusions are more likely to lead to receptor activation (w_b ≈ q_b).