High levels of Pax2a bias otic contribution. (A-B″) Zebrafish embryos expressing bi-directional heat-shock-inducible plasmid (heat-shocked at 12 and 14 hpf) driving egfp (A-A″) or pax2a (B-B″) in one direction and dTomato (dTom) in the other. Arrows indicate Pax2a-misexpressing cells sequestered to otic placode. Arrowheads indicate cells segregated to EB placodes. (C) Relative contribution of dTomato+ cells to the otic vesicle and EB placodes at 24 hpf in EGFP (controls) and Pax2a (overexpression) embryos. Pax2a-overexpressing cells are prone to otic contribution, segregating less frequently to EB placodes versus controls (n≥192 cells from 8-12 embryos per condition; χ2-test; **P<0.016, ***P<0.001). f, facial placode; g+v, glossopharyngeal/vagal placodes; HS, heat-shock; ov, otic vesicle. Scale bars: 50 μm.