Fig. 5. No-flux conditions modelling a bud surrounded by two other buds show coherent smooth muscles formation.

(A) Schematic representation of an early lung bud. Due to symmetry considerations, the lung bud in the middle can be modeled with no-flux boundary conditions. (B) Smooth muscles distribution (colormap white (low concentration), red (intermediate), black (high)) and FGF10 (black contours) at τ = 120 in case of no-flux conditions (in green) at the two exterior boundaries of the stalk. All parameters are as in Table 1.