Fig. 4. Abd-B m and Abd-B r expression in mature genital discs. (A) Scheme representing the Abd-B transcription unit (not drawn to scale). The RNA is not represented. Red or blue rectangles represent exons of Abd-B m (red) or of Abd-B r (blue) transcripts, and black boxes represent coding regions. (B,C) Drawings of the female (B) and male (C) genital discs (ventral views), indicating the A8 and A9 primordia. The A10 primordium is on the opposite side in both discs. (D,F) Female discs hybridized with probes detecting the Abd-B m transcript (D) or the Abd-B r RNAs (`common' probe; F). (E,G) Male discs hybridized with Abd-B m (E) and Abd-B r (G) probes. Arrowheads in D and F indicate the A9, and in E and G, the A8 segment. Note that the Abd-B m transcript is expressed in the A8 of female and male discs, with some weak expression in the male A9, and that the Abd-B r transcript is present in the male and female A9, with some signal also in the female A8 (arrows; the most central expression in this primordium, out of focus, is the signal from the dorsal A9). Note also the low or absent Abd-B r expression in the anterior female A9.