Regulation of her3 and her9 expression by Bmp signaling. Expression of neurod4 (A-C), hes5 (D-F), her3 (G-I) and her9 (J-L) in wild-type (A,D,G,J), snail house/bmp7 (snh; B,E,H,K) and swirl/bmp2b (swr; C,F,I,L) mutant embryos at the one-somite stage. Lateral views with dorsal towards the right and ventral views (insets in K,L). (M) Schematic representation of the expression profiles of the proneuronal gene neurod4, and of her3 and her9 in the wild-type, snh and swr mutant embryos. Tg, trigeminal neurons. In the snhty68a mutant embryos, the RB neurons are lost and the primary interneurons are shifted ventrally (primary neurons are marked by neurod4 expression). In the swrtc300 mutant embryos, both the RB and primary interneurons are absent. In correlation with the expansion of the inter-proneuronal domains in these mutant embryos, the expression domains of her3 and her9 were strongly expanded ventrally. The expression reached the most ventral side in the swrtc300 mutant embryos.