Distribution and morphology ofdpr-expressing cells examined using GFP. The GFP was expressed using the GAL4/UAS system and examined by confocal microscopy. A–H, GFP expression indpr⁺/dpr heterozygous flies (dpr-GAL4, UAS-dpr/+). I,J, GFP expression in dpr homozygous flies (dpr-GAL4, UAS-dpr/dpr^1RH ). Tissues are oriented with the distal side to the right, except in G and H. Scale bar:A–J, 50 μm. A, Anterior wing margin. Two pairs of cells showing strong GFP staining (indicated bysmall arrows). The arrowheads indicate dendrites extending from the cell bodies to the base of chemosensory bristles. B, Merge of GFP (shown in A) with the Nomarski image. The large arrows indicate the bases of chemosensory bristles. No GFP expression was evident at the bases of the mechanosensory bristles. C, Distal region of the anterior wing margin. GFP staining was observed in pairs of cells (small arrows) and in hair shafts (large arrowheads); the spatial relationship of neuronal cell bodies and their corresponding hair shafts is evident. D, Merge of GFP (shown in C) with the Nomarski image. Thelarge arrows indicate GFP staining in hair shafts.E, Ventral view of the third tarsal leg segment. GFP-positive clusters each contain two neurons (arrows).F, Merge of GFP (shown in E) with the Nomarski image. Each GFP-positive pair of neurons was near the base of a recurved bristle, indicated by a large arrow. G, GFP-positive neurons in the proboscis occur singly or in groups of two (indicated by small arrowheads).H, Merge of GFP (shown in G) with Nomarski image. Chemosensory bristles (arrows) are innervated by GFP-positive neurons. I, Anterior wing margin in a dpr homozygote. J, Distal region of anterior wing margin in a dprhomozygote.