Building an Ommatidium: Geometry and Genes
The intricate network of the nervous system is woven layer upon layer during development; each stage of assembly serves as the scaffold upon which the next stage built. Many cellular and molecular mechanisms cooperate in this process, but unravelling their contributions is often hindered by the heterogeneity of neural tissue and the complexity of the neural network. The unit eye, or ommatidium, of the Drosophila compound eye is a simple network of interconnected cells that offers several advantages for studying these questions. Each ommatidium is a stereotyped assembly of a small number of photoreceptors and accessory cells in which each cell is precisely positioned by the contacts it makes with its neighbors; the remarkable regularity of the fly compound eye is the manifestation of a precise underlying pattern of cellular connectedness. The several hundred-fold reiteration of the ommatidium makes the compound eye a sensitive amplifier of this network. A wealth of genetic variants that perturb normal fly eye development has been isolated making these genes amenable to a host of genetic and molecular techniques. Finally, ommatidial assembly occurs in an easily accessible retinal epithelium and has been well characterized morphologically.
KeywordsRetinal Cell Pigment Cell Cone Cell Morphogenetic Furrow Retinal Epithelium
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