Fig. 1. Expression of SER is established progressively. (A) In early third instar leg discs (
72 hours AEL), a ring of SER expression is detected in the coxa. (B) At 78 hours AEL, a new ring of SER expression arises in the femur. (C) By 84 hours AEL, SER expression is detected in four domains, two of which are in the tarsal region (ta2 and ta5). (D) By mid third instar (96 hours AEL), SER is expressed in at least six prospective segments. It is unclear whether the new tarsal ring corresponds to ta1 or ta3; therefore, both the ta2 and the new ring are designated as ta. (E,F) Ultimately, by late third instar (120 hours AEL) SER is expressed in one ring per segment and expression continues during pupal stages. co, coxa; fe, femur; ta2,tarsal segment 2; ta5, tarsal segment 5; ti, tibia.
