Figure 4. Serial homology of the subcoxa and coxal segment shown by leg gap gene and Tc-ser expression in the embryonic mandible, maxilla and leg.

All views are distal to the top and lateral to the right except when otherwise indicated. Domains of Tc-ser are numbered 1 to 5 from proximal to distal. The black arrow shows the distal domain of Tc-dac expression, and the white arrowhead shows the expression of the proximal domain of Tc-dac expression. Gene expression is shown schematically for each panel. Gene expression is shown for the mandible (in a,d,g and j), the maxilla (in b,e,h and k) and leg (in c,f,i and l). (a) Expression of Tc-ser (blue) in the mandible. Lateral view. (b) Expression of Tc-ser (blue) in the maxilla. (c) Expression of Tc-ser (blue) in the leg. Lateral is to the left. (d) Expression of Tc-ser (blue) and Tc-dac (red) in a dissected mandible. (e) Expression of Tc-ser (blue) and Tc-dac (red) maxilla. (f) Expression of Tc-ser (blue) and Tc-dac (red) in a leg. Lateral is to the left. (g) Expression of Tc-ser (blue) and Tc-Dll (red) in a mandible. (h) Expression of Tc-ser (blue) and Tc-Dll (red) in a maxilla. There is an endite expression domain of Tc-Dll in the second segment, which is not present in the legs. (i) Expression of Tc-ser (blue) and Tc-Dll (red) in a leg. Lateral is to the left. (j) Expression of Tc-hth (blue) and Tc-dac (red) in a dissected mandible. (k) Expression of Tc-hth (blue) and Tc-dac (red) in a maxilla. The distal limit of Tc-hth expression in the maxilla can be related to Tc-ser expression by comparison with Tc-dac expression. Tc-hth is expressed up to the trochanteral-3 domain of Tc-ser expression and therefore co-expressed with the third Tc-ser domain in the maxilla and legs. (l) Expression of Tc-hth (blue) and Tc-dac (red) in a leg. Lateral is to the left. (m) Diagram showing leg gap gene expression corresponding to domains of Tc-ser expression.