Fig. 5. Expression of Phox2a (A,D,G, arrow), Pax6 (B,E,H, arrows) and Pax3 (C,F,I arrows) was analysed in control embryos at stage 14/15 (A-C), stage 26/27 (D,E) and stage 22 (F), and in Noggin-treated embryos at stage 26/27 (G,H) and stage 22 (I). (A-C) Wild-type embryos; (D-F) control embryos treated with CHO cells; (G-I) Noggin-expressing CHO cell treatment. Note that Phox2a expression at stage 14/15 is observed within the Pax3 and Pax6 domain (compare A-C). In controls, at stage 26/27, expression of both Phox2a and Pax6 is localised to ventrolateral regions of r1 (D,E). Pax-3 expression at stage 22 is observed in a large region that excludes dorsal midline and most parts of the ventral region (F). After application of Noggin-expressing cells, Phox2a and Pax6 expression is observed in the dorsal region of the neural tube (G,H). Pax3 expression is now expressed in the entire dorsal region (I).
