Cell fate specification in the developing Drosophila retina.

The developing Drosophila retina provides an excellent experimental system in which to address questions of cell fate choice and patterning. By focusing first on a detailed morphological description of eye development and more recently on the genes required for its development, the first steps have been taken toward understanding how these two aspects combine to direct cell fate in the retinal neuroepithelium. In addition, developing cell types emerge within the ommatidium in stereotyped patterns; these patterns may provide further clues regarding the mechanisms involved in cell fate choice. Previous reviews have focused on the detailed morphological description of, and molecules involved with, retinal development. This review focuses on current progress in understanding the role of several genes that play critical roles in retinal development, with special emphasis on how they define symmetric groups of cells within each ommatidium. In addition, the role of local cell interactions in directing cell fate is assessed.