Specification and patterning of the respiratory system

This chapter focuses on the mechanisms of specification, expansion and patterning of the respiratory progenitors during lung development. Currently little is known about the signals required for induction of the respiratory lineage and that generate cellular diversity in the respiratory epithelium. Studies in different species implicate Fgfs, retinoids, Wnt, and transcription factors such as Tbx, Nkx2 and Sox in the regulation of the initial developmental events in the lung. We will review the role of these regulators and how they interact. We will also discuss aspects related to the identification and behavior of putative stem/progenitor cells of the lung.