Fig. 5. Misexpression of Spalt4 in otic placodes can prevent the formation of otic vesicles. (A) An embryo electroporated with a control plasmid gives rise to a normal otic vesicle (ov) expressing Sox10. (B) An embryo electroporated with a Spalt4-expressing plasmid gave rise to a flat ectoderm (oe) expressing Sox10 where the otic vesicle is normally located. (C) Section through an embryo electroporated with a control plasmid at the otic vesicle level shows GFP expression in the closed otic vesicle. (D) Same section as in C showing expression of Sox10 in the lateral half of the otic vesicle. (E) Section through an embryo electroporated with a Spalt4-expressing plasmid at otic vesicle level shows GFP-positive cells in the thickened epithelium where the otic vesicle would normally be located. (F) In situ hybridization with Sox10 RNA probe. Same section as in E. (G) Section through an embryo electroporated with a Spalt4-expressing plasmid at otic vesicle level shows GFP expression in the thickened epithelium where the otic vesicle would normally be located. (H) Same section as in G using a Pax2 antibody. (I) Section through otic vesicles of an embryo electroporated with a control plasmid. (J) Same section as in (I) showing Six1 expression in the ventral half of the otic vesicle. (K) Section through the otic ectoderm of an embryo electroporated with a plasmid overexpressing Spalt4. (L) Six1 expression in the same section as in (K). ov, otic vesicle; oe, otic ectoderm; hb, hindbrain.