FishFace

By 24 hpf, neural crest cells have populated the two anterior pharyngeal arches (pa1, pa2). The anterior region of pharyngeal arch 1 surrounds the oral ectoderm (oe), which is GFP-negative in fli1a:EGFP transgenic fish. Cells positioned ventral to the oral ectoderm in pharyngeal arch 1 contribute to Meckel’s cartilage and associated bones, while those positioned dorsally and posteriorly contribute to the palatoquadrate and portions of the neurocranium, along with their associated bones. Cells positioned ventrally in the second pharyngeal arch contribute to the ceratohyal and associated bones, while those positioned dorsally and posteriorly contribute to the hyosymplectic and associated bones. The first pharyngeal pouch (pp1), which is GFP-negative in fli1a:EGFP transgenic fish, dorsally separates pharyngeal arches 1 and 2, which contact each other ventrally.