CELL FATE SPECIFICATION IN THE DEVELOPING DROSOPHILA RETINA

The developing Drosophilia retina provides an excellent experimental s ystem in which to address questions of cell fate choice and patterning . By focusing first on a detailed morphological description of eye dev elopment and more recently on the genes required for its development, the first steps have been taken toward understanding how these two asp ects combine to direct cell fate in the retinal neuroepithelium. In ad dition, developing cell types emerge within the ommatidium in stereoty ped patterns; these patterns mag provide further clues regarding the m echanisms involved in cell fate choice. Previous reviews have focused on the detailed morphological description of, and molecules involved w ith, retinal development. This review focuses on current progress in u nderstanding the role of several genes that play critical roles in ret inal development, with special emphasis on how they define symmetric g roups of cells within each ommatidium. In addition, the role of local cell interactions in directing cell fate is assessed.