Figure 8.

Proposed model for the behaviors and roles of mesenchymal compartments in the embryonic mouse lung

The embryonic pulmonary mesenchyme consists of sub-epithelial and sub-mesothelial compartments that are regulated by Wnt signaling and that are characterized by distinct migratory behaviors and cortical forces. Cells can migrate between compartments and sub-epithelial cells give rise to airway smooth muscle. Activating Wnt signaling expands the sub-epithelial compartment, activates the earliest stages of smooth muscle differentiation, and leads to the local accumulation of F-actin in the mesenchyme to constrain the branching epithelium.