Fig. 2. Expression of the lacZ gene in the Abd-B^lac1 insertion. (A-F) ß-galactosidase expression (orange) in Abd-B^lac1 embryos, also stained with anti-engrailed antibody (brown) to mark parasegments (A,C,E), compared with Abd-B protein expression in wild-type embryos (B,D,F). (A,B) Stage 11 embryos; (C,D) stage 13 embryos; (E) a stage 16 embryo; (F) a stage 14 embryo. Numbers indicate parasegments. Note that ß-galactosidase expression in the stage 11 Abd-B^lac1 embryo extends from PS12 to PS14 (A), whereas in wild-type embryos at this stage there is no Abd-B protein expression in PS12 (B). Note also strong ß-galactosidase expression in the ventral cord of the stage 16 Abd-B^lac1 embryo (E, arrow). (G) ß-galactosidase expression in a stage 16 Pc³ Abd-B^lac1 embryo, showing the absence of PS12 specific signal.