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Fig. 2. Effects on branchial arch development of the RARß agonist BMS453.
External (A-D) and histological (E,F) aspects of the pharyngeal region of
wild-type embryos after 48 hours in culture without retinoid (vehicle; A,C,E)
or in the presence of the RARß-selective agonist (B,D,F). Embryos in C
and D were injected with ink. Frontal histological sections (E,F) were
obtained from comparable levels of the embryos. A1-A3, aortic arches 1 to 3,
respectively; A1-2 fused first and second aortic arches; B1-B3, branchial
arches 1 to 3, respectively; B1-2, fused first and second branchial arches; D,
dorsal aorta; H, heart; P1, first pharyngeal pouch. White arrowhead (A)
indicates the first branchial cleft. Scale bar in F: 200 µm in E,F.