Dissection techniques for pupal and larval Drosophila eyes

INTRODUCTIONThe Drosophila eye has been used to study a broad range of topics, such as signal transduction, cell-fate specification, morphogenesis, and cell death. The eye has a relatively simple cellular architecture: the ommatidia (unit eyes of the compound eye) are composed of a small number of cells, and these cells can be readily identified on the basis of their shape and location within an ommatidium. Also, because the eye is a monolayer epithelium, all cells can be viewed in whole-mount preparations in both the larval imaginal disc and the pupal eye. Mosaic analysis is a powerful genetic tool that is routinely used in the eye to determine a given cell's requirement for a gene of interest. Such analyses are possible because cell fates are determined on the basis of positional cues. Furthermore, pattern formation proceeds as a wave of morphogenesis sweeps across the eye disc. Thus, all early patterning events are laid out in a single imaginal disc preparation. A final attractive feature of the eye is that it is dispensable for viability and development, and therefore a number of tools have been developed for its manipulation.