Retinal determination the beginning of eye development.

The road to producing an eye begins with the decision to commit a population of cells to adopting an eye tissue fate, the process of retinal determination. Over the past decade and a half, a network of transcription factors has been found to mediate this process in all seeing animals. This retinal determination network is known to regulate not only tissue fate but also cell proliferation, pattern formation, compartment boundary establishment, and even retinal cell specification. The compound eye of the fruit fly, Drosophila melanogaster, has proven to be an excellent experimental system to study the mechanisms by which this network regulates organogenesis and tissue patterning. In fact the founding members of most of the gene families that make up this network were first isolated in Drosophila based on loss-of-function phenotypes that affect the eye. This chapter will highlight the history of discovery of the retinal determination network and will draw attention to the molecular and biochemical mechanisms that underlie our understanding of how the fate of the retina is determined.