Fig. 1.

Placodal distribution of Sox3-immunopositive cells in relation to Six1, NeuroD, Delta1 and Ngnr1 expression in transverse sections through stage 26 embryos. Each section is shown in bright field (A₁-I₁: gene expression), red fluorescence (A₂-I₂: Sox3 protein), and a superposition of these two with blue DAPI fluorescence (A₃-I₃). White asterisks indicate placodally derived cranial ganglia (main body of ganglia out of level of section in B, C and G). Black asterisks mark endodermal Sox3 nuclei. A-C: Six1 expression domains in otic vesicle (A), anterodorsal lateral line (B) and facial epibranchial (C) placodes encompass Sox3 immunopositive nuclei (arrows). D-F: NeuroD is expressed in ganglia derived from otic vesicle (D), anterodorsal lateral line (E) and facial epibranchial placodes (F) immediately abutting Sox3-positive placodal cells (arrows). G-I: Delta1 expression in the otic vesicle (G), and the anterodorsal lateral line and glossopharyngeal epibranchial placodes and ganglia (H upper and lower part, respectively) and Ngnr1 expression in the facial epibranchial placode (I) overlap with some (black arrows) but not all (white arrows) Sox3-cells. Bar in I: 50 μm (for all panels).