Fig. 2

Both ampullary organs and neuromasts express transcription factor genes essential for hair cell development, and selected putative Atoh1 targets.

(A–D) In situ hybridization for paddlefish Atoh1 at stages 33, 37, 39 and 46, respectively. (E–H) Sox2 immunostaining at stages 34, 37, 41 and 46, respectively. (I,J) Higher-power views of stage 46 skin-mounts of Atoh1 (I) and Sox2 (J). Dotted lines indicate approximate boundaries of neuromast containing lateral line canal lines. (K,L) In situ hybridization for Pou4f3 at stage 46 reveals expression in both ampullary organs and neuromasts. (M,N) In situ hybridization for Sox1 at stage 39 shows expression in the posterior lateral line primordium (pllp) and ampullary organs erupting on the operculum. (O,P) At later stages, Sox1 is maintained in ampullary organs and expressed in neuromast canal lines, as shown here at stage 45. Abbreviations: ao, ampullary organ; e, eye; nm, neuromast; ov, otic vesicle, pllp, posterior lateral line primordium. Scale bars: A-H,K,M-O, 200 µm; I,J,L,P, 100 µm.