Figure 4.

Prevailing model of the regulation of fluid dynamics by airway smooth muscle during branch elongation. (A) When smooth muscle is relaxed luminal fluid flow is weak and transmural pressure (ΔP) is low and non-localized. Mesenchymal Fgf10 flux is reduced. (B) During peristalsis, luminal fluid flow increases, creating high localized transmural pressure, which directs branch elongation, as well as increases mesenchymal Fgf10 concentration and flux around the tip. Dark and light blue ovals represent localized sources of high and low Fgf10 expression, respectively.