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Fig. 9
Neural crest cells require the reception of Bmp signaling for palatogenesis in zebrafish. A,B,C,F,I: Whole-mount Alcian Blue/Alizarin Redstained 5 days postfertilization (dpf) zebrafish. D,E,G,H: Genetic mosaics in which Alexa-568 dextran labels donor cells (red). A,B: Ventral views (C,F,I) dorsal views (D,G) lateral views (E,H) ventral views focused on the palatal skeleton. A: Wild-type and (B,C) smad5 mutant zebrafish larvae. B: In the pharyngeal skeleton, Meckel′s cartilages are reduced and fail to meet at the midline symphysis, asterisk. Additionally, the ceratohyal cartilage is fused to the first ceratobranchial cartilage black arrowhead. C: Only small remnants of the trabeculae remain in the palatal skeleton of smad5 mutants. D–F: Transplantation of wild-type neural crest cells into smad5 mutants partially rescues the palatal skeleton. D: At 30 hours postfertilization (hpf), wild-type neural crest cells (yellow) contribute readily to the first pharyngeal arch of smad5 mutant embryos. (E,F: By 5 dpf these wild-type cells have populated the palatal skeleton (white arrowheads in E) and substantially rescued the trabeculae and partially rescued the ethmoid plate (white arrowhead in F). G–I: In reciprocal transplants, (G) smad5 mutant neural crest cells readily condense on the oral ectoderm in the maxillary and frontonasal domains. H: At 5 dpf, many smad5 mutant cells remain in the region of the developing palate; however few of these cells contribute to the palatal skeleton and (I) the trabeculae and ethmoid plate are both disrupted on the side of the transplant (white arrowheads). M, Meckel′s cartilage; ch, ceratohyal; cb1, first ceratobranchial; t, trabeculae.