Fig. 4. In jeb^weli and mili^Alk mutants the founder cells of the circular visceral musculature are not determined. The development of the visceral mesoderm in wild-type (WT), jeb^weli and mili^Alk mutants as visualised by Fas3 expression (red in A-I). (A-F) Stage 11, (G-I) stage 15-16 and (J-L) stage 14. The nuclei of the founder cells are marked by rP298-lacZ expression (green in D-F, brown in J-L). In jeb^weli and mili^Alk mutants at stage 11, the more columnar-shaped founder cells are missing. Only cells that display the more globular shape of the fusion-competent myoblasts (fcm) are present (B,C,E,F). Additionally, the founder cell marker rP298-lacZ is absent in the visceral mesoderm in these mutants (E,F). The rP298-lacZ-positive cells, which can be observed over the fcms of the visceral mesoderm in D-F belong to the somatic mesoderm. At later stages, there are no signs of visceral musculature in either mutant (stage 16, arrowheads in H-I). (J-L) The founder cells of the somatic mesoderm are not affected in these mutants as visualised by rP298-lacZ expression (stage 14, K,L compare with J).