Fig. 7. Oral expression of foxa is required for mouth formation. Red indicates foxa MASO-injected cells; green indicates control cells. (A,D) Diagram of the experiment. Reciprocal combinations of animal and vegetal halves were recombined. (B,C) Control animal half, showing normal mouth (arrowhead, C). The foxA MASO vegetal half (red) produces a truncated gut, with most of the red cells becoming SMCs, and extra pigment cells (compare black cells in C and F). (E,F) foxa MASO-injected animal half (red) produces ectoderm with no mouth. The control vegetal half (green) produces a normal gut, including foregut that leads to a dead end. (B,E) DIC images superimposed on fluorescent images. (C,F) Fluorescent image only at a slightly higher magnification, focused on the mouth region.