Fig. 5
From: Development of hypobranchial muscles with special reference to the evolution of the vertebrate neck
The relative position of the pericardium and pharyngeal arches. Nkx2–5 (a), Tbx1 (b), and Tbx5 (c) expressions in S. torazame at the stage 25 from the lateral view. Nkx2–3/2–5/2-6A (d), Tbx1/10A (e), and Tbx4/5 (f) expressions in the lamprey at the stage 26 from the lateral view. Nkx2–5 and Tbx5 homologs were expressed in the cardiac mesoderm. Tbx1 cognate genes were detected in the pharyngeal arch mesoderm and endoderm. Note that the cardiac mesoderm resided ventral to pharyngeal arches in shark embryos, whereas the cardiac mesoderm lay posterior to the arches in lamprey embryos. ba, branchial arch mesoderm; ha, hyoid arch mesoderm; ht., heart tube; ma, mandibular arch mesoderm; ot, otic vesicle; pcm, pericardial mesoderm; pe, pharyngeal endoderm. Scale bars, 200 μm