The role of neural crest progenitor number in establishing species‐specific differences in jaw size

Abstract

ObjectiveTo test the hypothesis that differences in jaw size are dependent upon the number of neural crest progenitor cells in two morphologically distinct birds, duck and quail.MethodsBrain regionalization and NC population were established by performing whole mount in‐situ hybridization. Neural crest progenitor number was altered by surgical manipulation.ResultsBrain regionalization markers reflect differences in the shape of the midbrain, a NC precursor domain known to contribute to the jaw, showing that duck embryos have a wider midbrain than quail embryos. This morphological difference correlates with a slight increase in the number of Sox10‐positive migrating neural crest cells at HH10, but not in the number of Pax7‐positive neural crest precursors at HH8. Surgical ablation of neural crest precursors at HH9 leads to a reduction in Sox10‐positive migrating neural crest. Depletion in migrating neural crest contributes to asymmetric development of the jaw. Jaw asymmetries decrease as development proceeds, suggesting a compensatory response of post‐migratory neural crest within the mandibular arch environment.ConclusionOur data indicate that a combination of factors, including neural crest cell biology and epithelial‐mesenchymal interactions, determine species‐specific differences in jaw size.Supported by: HFSP Long‐Term Fellowship LT01061/2007‐L and NIH grant NIDCR R01 DE016402.