Fig. 5.

Structures affected in both Drosophila and humans with sal mutations and the genetic hierarchies governing ear development. (A) Dll regulates both sal and ato during development of the Drosophila auditory apparatus (38, 48). (B) Dll, sal, and ato homologs, the Dlx, Sall, and Ath genes, respectively, are involved in vertebrate ear development (8, 11-13, 54-57). If their genetic relationships prove similar, it would support the idea that a common vertebrate/invertebrate ancestor possessed a primitive ear whose development was governed by these genes.