Organogenesis of the Drosophila respiratory system

The trachea (Drosophila respiratory organ) is a highly branched tubular network, which has emerged as a premier model system for the investigation of molecular and cellular mechanisms of tubular organogenesis. Genetic and molecular analyses of tracheal development have implicated an organogenetic network composed of over two hundred genes, several of which function in highly conserved cell signaling pathways. Tracheal construction incorporates the assembly of multicellular, unicellular and subcellular tube architectures, providing an instructive case study for iterative utilization of the same cell signals under diverse developmental contexts. These signals direct cell specification, migration and branch architecture. Assembly of the tracheal tubular network is driven by several morphogenetic processes, which include invagination, collective cell migration, branch fusion, cell shape changes and cell rearrangements. In addition to assembly, the genetic network also serves to control tubule size while exhibiting a remarkable degree of developmental plasticity. Here, we review all of tracheal development from specification of the primordia in early embryos through the acquisition of terminal architecture to the final clearance of the airway coincident with the onset of tracheal function.