H. W. Jackson et al. 58pitx2a after the opening of the primary mouth and disrupted expression of Wnt5b which is consistent with disrupted chondrocyte stacking. Strong upregulation of dorsal mesodermal frzb expression in the prechordal plate of Wnt9b morphants suggests a role for Wnt9b in primary mouth induction or maintenance. Collectively these results argue that Wnt9b has a much earlier developmental requirement. This work draws attention to potential vertebrate homologies that pattern CNCC and facial outgrowth and therefore calls for a reexamination of Wnt9b's role during mammalian craniofacial development.