Cuticle preparation of Drosophila embryos and larvae

The Drosophila embryonic ventral epidermis has served as a unique tissue for the genetic analysis of patterning. Two types of epidermal cells are easily distinguished: those that secrete short, thick hair-like structures called denticles and cells that only secrete smooth cuticle. Denticle-secreting cells form segmentally repeated belts. Within each belt, six types of denticles can be recognized according to size, shape, and orientation (types 1-6). They are arranged in a stereotypical manner within each denticle belt. This pattern results from the spatially organized activation of several signaling pathways during embryogenesis. Cuticle patterns therefore provide a sensitive readout of signaling activity and other patterning mechanisms. Here, I describe methods of preparation and analysis of cuticles from 1st instar larvae as well as from 3rd instar larvae. In addition, a protocol to simultaneously analyze cuticles and beta-galactosidase activity of embryos expressing lacZ reporter genes is presented.