Zebrafish alx1 and alx3 functions are required in migratory anterior cranial neural crest. (A) A schematic fate map of 20-somite-stage cranial neural crest at 4 dpf. The anterior cranial neural crest (aCNC) contributes to the median element of the anterior neurocranium (ANC) while the maxillary stream of migrating CNC (MxCNC) contributes to the maxillary prominence and subsequently coalesce to form the lateral element of the ANC. B-Q: aCNC and MxCNC were labeled by kaede photoconversion (magenta) at 20 somites and imaged immediately, allowed to develop until 4 dpf and imaged again (20-somites images: star sign marks the anterior; 4 dpf images: anterior to the left). alx1-/-;alx3 crispants exhibit a midline cleft (K,M,O,Q) with malformed median and lateral elements. The aCNC and MxCNC migrating streams failed to reach their destinations and ectopically localized along the migratory path (arrowheads in K,M,O,Q). Note that ocular fluorescence is due to the presence of iridophores and retinal pigment epithelium in the eye, not to kaede fluorescence at 4 dpf. Arrowheads point to photoconverted cells and their progeny. Dotted line outlines the shape of the photoconverted cells at 4 dpf. Scale bar: 100 µm.
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