Loss of six1 causes craniofacial dysmorphologies.
A-B. Whole-mount Alcian blue staining of Xenopus tropicalis tadpoles shows that while six1-heterozygotes (six1+/−) present no detectable defects in the branchial arch-derived craniofacial cartilages, six1-nulls (six1−/−) have hypoplastic and deformed Meckel’s (m), quadrate (q), ceratohyal (ch), and branchial arch (b) cartilages and hypoplastic otic capsule (oc).
C-D. Transverse section of tadpoles in A-B at the level of the otic capsule (oc) showing hypoplasia of this structure in six1-null tadpoles (D). hb. hindbrain. Bar. 100μm.
E-F. Whole-mount Alcian blue staining of E14.5 mouse embryos showing absent otic capsule (oc*) and deformed Meckel’s cartilage (m) in Six1-null embryos.