Fig. 8. Expression of Cer1 and Sox17 in the presumptive foregut of Mixl1^–/– embryos. (A-C) Lateral (A,B) and dorsal (C) views of Cer1 expression in wild-type (+/+) (A) and Mixl1^–/– (–/–) embryos (B,C, same specimen). Expression is seen in the two newly formed somites and anterior presomitic mesoderm in both wild-type and mutant embryos, but ectopic expression (arrows) is found in the endoderm of the presumptive foregut of the mutant embryo. (D) Histological section at the plane shown in C shows Cer1 expression in the rudimentary foregut pocket. Lateral (E), anterior (F) and dorsal (G) views of early-somite stage wild type (E) and Mixl1^–/– embryos (F,G) showing Sox17 expression in the endoderm of the presumptive foregut (arrows in G,H) but not in the hindgut of the mutant embryo. (H) Transverse section at the plane shown in G.