Fig. 7.

A–D,Voila¹/UAS–lacZ expression pattern 24 hr after puparium formation. In legs (A), wings (B), and labial palps (C), strong expression is seen in developing gustatory sensilla (arrowheads) and afferent nerves (arrows). In the legs, strongly and moderately stained elements can be distinguished. For example, in the metathoracic leg shown in A, approximately 10 intensely labeled cell clusters are present in the two distalmost tarsal segments (left), corresponding to known numbers of taste bristles. In addition, future mechanosensory bristles exhibit moderate expression (arrowhead). On the wing margin (B), approximately 40 bristle sensilla are intensely stained (arrowhead), reflecting the numbers of adult taste bristles. Weak expression is also present in certain wing veins (B, asterisk) and in the fat body of the palps (C, asterisks).D, The entire second and third antennal segments (open and filled circles, respectively) are strongly labeled. The transient staining of nerves between the antennal segments (arrowheads) and toward the brain (arrows) suggests that at least some olfactory neurons express GAL4 at this stage. Scale bar, 100 μm.