Purpose: Understand how the misexpression of key sensory cell determinant POU IV affects cell type specification of various sensory neurons in the peripheral nervous system in Ciona. Methods: CesA>POU IV (2.5ng/?l) + CesA>GFP (5.0ng/?l) injected eggs and control eggs were fertilized side by side, and allowed to develop to the late tailbud stage (13.5h after fertilization at 18°C). For each sample, 120 morphologically normal embryos were used for single cell RNA-seq assays. Dissociation of the embryos and single cell RNA-seq assays by 10x Genomics chromium system were done as described in 9. Horie R. et al., Shared evolutionary origin of vertebrate neural crest and cranial placodes. Nature 560, 228-232 (2018). Results: Misexpression of POU IV leads to the formation of Synthetic Cell Types that exhibit properties of other sensory neurons, especially those of bipolar tail neurons (BTNs) and a synthetic gene battery that is not found in any wildtype sensory neuron. Overall design: Single-cell RNA-seq data for control and POU IV-misexpressed Ciona intestinalis embryos at late tailbud (LTB) stage.