Figure 7

A circular gap of Tc-dac expression in the outer lobe of the mandible is filled by a ‘cap’ of Tc-ser expression. All views are ventral with anterior to the left unless otherwise indicated. Gene expression was detected by in situ hybridization. (A) Tc-dac (red) and Tc-ser (blue) expression in the mandible of a germ band extending embryo. Ventral view with distal at top. Tc-dac is expressed continuously in the outer lobe of the mandible. A ring of Tc-ser (white arrow) which we interpret as the distal boundary of the subcoxa is indicated (Coulcher, manuscript in preparation). (B) Tc-dac (red) and Tc-ser (blue) expression in a maxilla of the same embryo as shown in A. Ventral view with distal top. Tc-dac is expressed in the distal part of the developing lacinia endite. The lacinia and galea endite lobes have formed. (C) Tc-dac (red) and Tc-hth (blue) expression in a germ band extended embryo. A circular region of Tc-dac expression is missing in the outer lobe (asterisk). Tc-hth is expressed in the very distal part of the inner lobe, and is lacking entirely from the outer lobe. (D) Tc-dac (red) and Tc-hth (blue) expression in a germ band extended embryo. The circular gap in expression (asterisk) widens as development progresses. (E) Tc-dac (red) and Tc-ser (blue) expression in a dissected mandible. A ‘cap’ of Tc-ser expression is expressed within the circular gap of Tc-dac expression in the outer lobe (white arrowhead). The subcoxal ring of Tc-ser expression is indicated with a white arrow. (F) Tc-ser expression in a dissected mandible. Lateral view with distal top. A ‘cap’ of Tc-ser expression is present at the distal-most point of the outer lobe (white arrowhead). The subcoxal ring of Tc-ser expression is indicated with a white arrow.