During development, simple, instructive signals can initiate the formation of elaborate patterns. An example of such a system has now been described for the formation of two appendages that are used for respiration in the fruitflyDrosophila melanogaster. The pattern is formed by stimulation and then inhibition of the epidermal growth factor receptor through both paracrine and autocrine mechanisms.
- Norbert Perrimon
- Joseph B. Duffy
