Figure 5.

Variations in Wing Position Correlate with Changes in Tbx5, Hoxb4, and Hoxb9 Expression Domains in the LPM

(A–C) Alcian blue-Alizarin red staining of chicken (A; E20), zebra finch (B; E13), and ostrich (C; E37). Red arrowheads point at the wing position level (15^th, 13^th, and 18^th vertebrae in chicken, zebra finch, and ostrich embryos, respectively); red dots mark each cervical vertebra.

(D–F) Tbx5 expression in stage 18 chicken (D), zebra finch (E), and ostrich embryos (F). The position of Tbx5 posterior border of expression is indicated in somite number. (E’) and (F’) are higher magnification of (E) and (F), respectively.

(G–I) Hoxb4 expression in chicken (G; 20-somite stage), zebra finch (H; 20-somite stage), and ostrich embryos (I; 34-somite stage). The position of Hoxb4 posterior border of expression is indicated in somite number. (H’) and (I’) are higher magnification of (H) and (I), respectively.

(J–L) Hoxb9 expression in chicken (J; 20-somite stage), zebra finch (K; 20-somite stage), and ostrich embryos (L; 36-somite stage). The position of Hoxb9 anterior border of expression is indicated in somite number. (K’) and (L’) are higher magnification of (K) and (L), respectively.

Dashed black lines show variation in posterior-anterior border of expression in zebra finch (E’, H’, and K’) and ostrich embryos (F’, I’, and L’) compared to chicken embryo (represented by red asterisks).

Scale bars are 3 mm in (A)–(C) and 100 μm in (D)–(L), (E’), (F’), (H’), (I’), (K’), and (L’).