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Fig. 2 Depletion of dmrt2b impairs cranial cartilage development. (A) Generation of dmrt2b mutant using the CRISPR/Cas9 system. The dmrt2b mutant has a four base deletion that results in expression of a truncated protein lacking the DM domain. (B,C) Morphological defects in dmrt2b mutants at the indicated stages. (D) Anatomy of the pharyngeal arches and head skeleton in dmrt2b mutants. Red arrowheads indicate branchial arches. (E,F) Alcian Blue staining of head cartilages at 96 hpf. Cartilage defects in dmrt2b mutants and morphants were abrogated by injection of dmrt2b mRNA (F). (G) Anatomy of the pharyngeal arches and head skeleton in embryos injected with indicated shRNA expression plasmids. Red arrowheads indicate branchial arches. (H) Alcian Blue staining of head cartilages in shRNA expression plasmid injected embryos. Scale bar: 100 µm. ac, auditory capsule; not, notochord; pc, parachordal; abc, anterior basicranial commissure; ep, ethmoid plate; tc, trabeculae cranii; m, Meckel's cartilage; bh, basihyal; ch, ceratohyal; pq, palatoquadrate; hs, hyosymplectic; cb, ceratobranchial. Scale bars: 200 µm (B,C), 100 µm (D–H).