Fig. 3. even-skipped expression in the posterior growth zone and germband. Germband stage embryos are stained for even-skipped (purple) and engrailed (orange). (A1) Early germband with Of'eve accumulation in growth zone. Third thoracic segment is marked (T3). The growth zone is large. (A2) Higher magnification of embryo shown in A1, showing appearance of first abdominal Of'en stripe, coincident with a stripe of Of'eve. (B) Mid-germband stage embryo stained only for Of'eve. The midline region of the early stripe is still contiguous with the growth zone patch, indicating that this stripe is still in the process of leaving the growth zone. (C1) Mid-germband stage embryo. Of'eve expression is maintained in the growth zone and in three stripes just anterior to growth zone expression. Growth zone is now smaller than in A1. (C2) Higher magnification of embryo shown in B1, showing coincident expression of Of'eve and Of'en in three early segments. Of'eve is most strongly expressed in the younger (more posterior) segments, while Of'en is expressed more strongly in older (more anterior) segments. Thus, Of'eve expression is fading just as Of'en expression initiates. (D1) Embryo at end of germband elongation. Growth zone expression of Of'eve fades. (D2) Higher magnification of embryo shown in D1. Final Of'eve stripe is coincident with tenth abdominal Of'en stripe. Remaining posterior dot of Of'eve may represent anal ring expression. (E) Cartoon showing birth and progressive maturation of Of'eve germband stripes. Early stripes seem to `peel' away and are often contiguous with growth zone patch. Scale bars: 200 µm for A1,C1,D1; 100 µm for A2,B,C2,D2.