Eyeless/Pax6 initiates eye formation non-autonomously from the peripodial epithelium.

The transcription factor Pax6 is considered the master control gene for eye formation because (1) it is present within the genomes and retina/lens of all animals with a visual system; (2) severe retinal defects accompany its loss; (3) Pax6 genes have the ability to substitute for one another across the animal kingdom; and (4) Pax6 genes are capable of inducing ectopic eye/lens in flies and mammals. Many roles of Pax6 were first elucidated in through studies of the gene (), which controls both growth of the entire eye-antennal imaginal disc and fate specification of the eye. We show that Ey also plays a surprising role within cells of the peripodial epithelium to control pattern formation.

Allocation of distinct organ fates from a precursor field requires a shift in expression and function of gene regulatory networks.

A common occurrence in metazoan development is the rise of multiple tissues/organs from a single uniform precursor field. One example is the anterior forebrain of vertebrates, which produces the eyes, hypothalamus, diencephalon, and telencephalon. Another instance is the Drosophila wing disc, which generates the adult wing blade, the hinge, and the thorax.