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Fig. 1. Expression of Pitx2c in the branchial arch mesoderm and aortic
sac. (A,B) Whole-mount images of 9.5 dpc wild-type embryos hybridized to a
Pitx2c-specific probe showing Pitx2c in left branchial arch
mesoderm (arrow in B). (C-E) Transverse serial sections through a 9.5 dpc
wild-type embryo hybridized to Pitx2c probe. Pitx2c
expression is denoted by arrows. (F,G) Coronal sections through a 9.5 dpc
embryo hybridized to a Pitx2c probe showing Pitx2c
expression in left branchial arch mesoderm near junction of the aortic sac
with the branchial arch artery (arrow in F). Pitx2c expression within
left aortic sac myocardium is denoted by arrowhead. In G, arrow designates
Pitx2c expression in dorsal branchial arch mesoderm in proximity to
forming branchial arch arteries. (H,I) Parasagittal section through a 10.5 dpc
embryo hybridized to Pitx2c probe. Arrow denotes ventral
Pitx2c expression while arrowhead in I indicates less abundant dorsal
Pitx2c expression. (J-M) Transverse sections through hearts of 10.5
dpc embryos hybridized to Pitx2c probe. Arrows in J,K,L indicate
Pitx2c expression in dorsal mesocardium, while arrowhead in L
indicates Pitx2c expression in left atrium. Arrows in M indicate
Pitx2c expression in right ventricular and interventricular
myocardium. as, aortic sac; ba, branchial arch; baa, branchial arch artery;
da, dorsal aorta; oft, outflow tract.