Fig. 6

Delta and ascl1a activity are necessary for intact taste bud organ formation. Genotypes are indicated in the top right-hand corner, embryonic stage and scale bar are in the bottom left-hand corner and marker expression is in the bottom right-hand corner. (A,B) Anterior is towards the top. Ventral confocal projections of the first branchial arch showing dlb overexpression in mib^–/– (B) compared with the wild-type sibling (A). (C-H,M,N) Anterior is towards the left. Ventral views. Asterisks in F-H indicate taste buds in the lips. 5HT⁺ and ascl1a-expressing cells are increased in number (D,H) and Calb2b⁺ and miR-200a-expressing cells reduced in number (D,F) in mib^–/– compared with the wild type (C,G and C,E, respectively). By contrast, 5HT⁺ (green) cells are absent and Calb2b⁺ (red) cells disorganized in the ascl1a^–/– pharynx (N) compared with the wild type (M). (I-L) Transverse sections of wild-type (I,K) and mib^–/– siblings (J,L) labeled with the pea3 probe. Arrows indicate pea3 expression in the pharyngeal arch epithelium (I,J, hyoid; K,L, b4). Scale bars: 15 μm. b1-b5, branchial arches 1-5; h, hyoid arch; m, mandibular arch; ov, otic vesicle; hy, hypothalamus.