Phenotypic and molecular effects of Hmga2 depletion on Xenopus embryos. (A) Stage 28 morphant embryos (ventral view) show a clear reduction (red arrowhead) of the pharygeal bulges (bracket) (cg, cement gland). (B) Schematics of normal NCC migration in Xenopus embryos; ma, hy, br, denote mandibular, hyoid, branchial streams, respectively. (C) Schematics of skeletal derivatives of NCCs at tadpole stage; m, q, c, cb denote Meckel's, quadrate, ceratohyal, ceratobranchial cartilages, respectively. (D–G) Pharyngeal skeletal phenotypes obtained following unilateral injections of MOs, as indicated; frequencies of the displayed phenotypes (D,E, morphant phenotype; F,G, wild type aspect) were 83% (n=130) and 76% (n=122) for MO1 and MO2 injections respectively. Typical phenotypes obtained with anti-hmga2 MOs consist in disruption or absence of branchial arch skeletal derivatives (stained in blue and indicated by arrows) and/or missing otic capsule (dashed circle) on injected side (left side in figure). (H) Effects of MO1 and MO2 on several NCC molecular markers as detected by WISH; expression was reduced by MO1 and MO2, respectively, in 75% and 76% of embryos for twist (n=124 and n=223); in 86% and 93% of embryos for sox9 (n=86 and n=84); in 85% and 73% of embryos for ap2 (n=66 and n=52); in 65% and 70% of embryos for dlx2 (n=61 and n=47). (I) The effects of MO2 are rescued by coinjection of hmga2 mRNA, as shown by recovery of normal twist expression (in 52% of embryos, n=99) and morphology (in 68% of embryos, n=187). Injected side was determined by GFP visualisation (D–G) and β-gal staining (H,I).