Establishment of smooth muscle and cartilage juxtaposition in the developing mouse upper airways

A balance of airway rigidity and elasticity is critical for uninterrupted airflow to and from the lungs. In the trachea and bronchi, this balance is achieved by the precise juxtaposition of smooth muscle (SM) and cartilage that together encircle the airway. We investigate how this juxtaposition is established during embryogenesis by using mouse mutants that lack either SM or cartilage in the developing lung. We demonstrate the nature of the antagonism between the nascent SM and cartilage lineages. Our results also reveal a role for cartilage in the proper differentiation of tracheal epithelium. Together these findings elucidate unique mechanisms of how airway SM or cartilage malformation may impact airway function.