Fig 2

Tg[atoh1a:GFP] embryos at 24hpf and at 48hpf were assayed for atoh1a (A, G), atoh1b (B, H), lhx2b (C-D, I-J) in situ hybridization, and anti-HuC (E-F, K-L) staining. Dorsal views of confocal MIP from dorsal stacks (A-B) or ventral stacks (C-L) with anterior to the left. A’-L’) Reconstructed transverse sections of the dorsal views in (A-L) at the level indicated with the white arrow depicted in (A-L) corresponding to r4/r5. All embryos displayed the atoh1a-progenitors and derivatives in green. Note that atoh1b cells derive from atoh1a:GFP progenitors (B’, H’), as well as the lateral lhx2b neuronal domain (see white asterisks in C’, I-I’), whereas the medial lhx2b neuronal column in r4 is devoid of green staining (see white arrowhead in C, I-I’). See that differentiated neurons organize in arch-like structures (yellow arrowhead in G-L). ov, otic vesicle; SAG, statoacoustic ganglion; r, rhombomere. Scale bars correspond to 50 μm.