Fig. 5. Loss of Cx43 expression in Cx43-PCKO embryos involves the cardiac neural crest distribution. (A) Low-power image of a wild-type E9.5 embryo in cross-section demonstrating first, second and third pharyngeal arches. (B,C) Corresponding high-power images of the first pharyngeal arch (PA1) (B) and the third pharyngeal arch (PA3) (C) in the E9.5 wild-type embryo immunostained for Cx43 (green stain). (D) Low-power image of an E9.5 Cx43-PCKO embryo. (E,F) Corresponding high-power images of PA1 (E) and PA3 (F) in the E9.5 Cx43-PCKO embryo immunostained for Cx43. Cx43 signal is similar in PA1, but reduced in PA3 at E9.5 in the Cx43-PCKO embryos compared with wild-type littermates. (G,H) Heart sections from E10.5 wild-type (G) and Cx43-PCKO (H) embryos immunostained for Cx43. Expression of Cx43 in the Cx43-PCKO heart is preserved at this stage. Propidium iodide nuclear staining is in red. Scale bar: 200 µm for A,D; 20 µm for B,C,E-H.