Fig. 9. SOX10 and HNK1 expression timing in quail, chick, and peafowl sections.

Transverse sections showing IHC for (A–N) SOX10 and (O–X) HNK1 in multiple stages of chick, quail, and peafowl embryos in (A-C, O– O⁴) HH8, (D–F) HH9, (G–I) HH11, and (P– S, U- X) HH10. Dorsal is to the top and ventral is to the bottom in section images while anterior is to the top and posterior to the bottom in whole mount images. SOX10 is not expressed at HH7 in any of the embryos (A–C) but is expressed in the dorsal neural tube during neurulation/NC specification at HH8 in all three organisms (D–F), is expressed in premigratory and migratory NC cells at HH9 during EMT (G–I), and is maintained in the dorsal neural tube in a small number of premigratory NC cells but is highly expressed in migratory NC cells at HH11 (J–L). (M) The number of SOX10+ cells were quantified for HH8 and HH9. At HH8, quail expressed more SOX10+ cells than chick (p = 0.001) and peafowl (p = 0.001), but by HH9 this difference was no longer statistically significant (p = 0.990). An ordinary one-way ANOVA statistical test was used. (N) Cell migration was measured from the neural tube midline to the furthest migrated cell for HH9 and HH11. At HH9, chick (p = 0.019) and quail (p = 0.009) cells migrated further than peafowl, but no statistically significant difference in distance was observed between quail and chick (p = 0.760). At HH11, no statistical difference was observed between species (p = 0.288 for chick and quail, p = 0.556 for chick and peafowl, and p = 0.244 for quail and peafowl). An Ordinary one-way ANOVA statistical test was used. Scale bars are as indicated in each whole mount panel or the first panel of each section row.