Embryos were scored as positive if some of the ectopic vesicles, or some ectopic structure in the 18 hour post-electroporation, expressed the gene. Tbx1 and Tbx3 had signal only in the post-otic ectoderm. Genes were considered pre-placode if they were expressed early and believed to be important in placode formation. Genes were considered placode genes if they were expressed as the otic placode forms or later.