Organ formation during embryogenesis requires the delicate orchestration of many different events. The specification of an organ primordium is tightly coordinated with the onset and control of morphogenetic events shaping that organ. In many cases, though, only the gene regulatory events that specify organ positioning and identity have been elucidated in much detail, whereas knowledge is scarce about the upstream regulation that controls effectors that directly drive morphogenesis. In this review, we will use the formation of the tubes of the salivary gland in the Drosophila embryo as a model system to illustrate what has been uncovered with regards to different phases of salivary gland morphogenesis: specification and positioning of the primordium, gland invagination, tube extension, organ positioning, as well as gland function. The salivary glands are an excellent model for the analysis of tube formation, as they are amenable to advanced imaging, genetic analysis and perturbance. In addition, upon specification by-and-large no cell death or division occurs, and thus the whole morphogenesis is driven entirely by cell shape changes and cell rearrangements.
Sidor, C., & Röper, K. (2016). Genetic control of salivary gland tubulogenesis in Drosophila. In Organogenetic Gene Networks: Genetic Control of Organ Formation (pp. 125–149). Springer International Publishing. https://doi.org/10.1007/978-3-319-42767-6_5