In early third instar leg discs (~72 hours AEL), a ring of Ser reporter expression is detected in the coxa. At ~78 hours AEL, a new ring of expression arises in the femur. By ~84 hours AEL, Ser reporter expression is detected in four domains, two of which are in the tarsal region (tarsal segment 2 and tarsal segment 5). By mid third instar (~96 hours AEL), Ser is expressed in at least six prospective segments with an additional tarsal segment and the tibia added. It is unclear whether the new tarsal ring corresponds to tarsal segment 1 or tarsal segment 3. Ultimately, by late third instar (~120 hours AEL) Ser is expressed in one ring per segment and expression continues during pupal stages. Sites of expression were identified relative to dac, hth, and Dll.

Expressed in concentric rings in the leg disc, in the region corresponding to the distal leg segments.