Fig. 4. Contribution of the EGO and MGO to the anterior mesoderm and foregut endoderm. (A) Gsc^lacZ-expressing tissue is found in the prechordal mesoderm and the foregut of the early-somite stage embryo. (B) EGFP-expressing cells derived from the transplanted EGO cells are distributed throughout the anteroposterior axis of the early somite stage host embryo, but only those that are localized (C-E) in the prechordal mesoderm (D), the foregut endoderm and the head processes (E) express the Gsc^lacZ transgene (arrowheads). (F) MGO-derived cells that are found in the cranial tissues of the early-somite stage host embryo also express Gsc^lacZ transgene when they are localized in the prechordal mesoderm (G) and the foregut (H, arrowhead), but not in the notochord of the hindbrain (box). Broken lines in C,F indicate the planes of section shown in D,E,G,H. Abbreviations: A-P, anterior-posterior axis; crm, cranial mesenchyme; hf, head-fold; som, somite; ne, neuroectoderm. Scale bars: 200 µm in A,B,C,F; 50 µm in D,H; 20 µm in E,G.