Fig. 3. EY and PB expression in the pre-pupal eye antennal disc. (A) Eye-antennal imaginal discs (DIC microscopy) after dissection from pre-pupae 8 hours after puparium formation. Eyes (ey), antennae (ant) and maxillary palps (mx) indicate the three adult structures derived from this compound disc. (B) PB expression revealed with a primary rabbit anti-E9 antibody and a HRP-coupled secondary antibody. Arrow indicates expression in the maxillary primordium. Higher magnification of the maxillary primordium is shown in the inset. (C) EY expression detected with a rabbit anti-EY. Arrowhead indicates EY expression in the eye disc. Arrow shows nuclear expression in the maxillary primordium. The inset shows higher magnification of the maxillary primordium. (D-G) pbGAL4>UASlacZ and EY expression in eye antenna disc. The lacZ immunodetection reflects PB GAL4 expression. Double immunostaining employed secondary antibodies revealing EY (red) and ß-galactosidase (green), and images were analyzed by confocal microscopy. (D,E) Maxillary primordium (boxed) is shown in more detail in F and G, respectively. In F, a small number of cells co-expressing PB and EY are indicated by the yellow arrowheads. The white open arrowheads show cells expressing only PB or EY. E and G are at a later stage, as judged by increased cell number. Cells express exclusively pb lacZ (green arrow) or EY (red arrow). The strong expression of lacZ seen in the antennal disc in D is ectopic expression in the distal antenna (see Kapoun and Kaufman, 1995). This expression is not visible in E.