Fig. 1. Normal expression of Tbx3 in the chick (A-F). (A) At stage13, Tbx3 is expressed in the presumptive forelimb (FL) and hindlimb (HL) levels (arrowheads). (B) At stage 16, Tbx3 expression is more robust in the posterior of the limb (arrowheads). (C) Stage16 section at the forelimb level. Tbx3 is expressed in the lateral plate mesoderm and somite. (D) Higher magnification of section in C. Tbx3 is present in the mesoderm but not ectoderm of the wing and in the ventrolateral lip of the dermomyotome. (E) Stage 19, Tbx3 is located in the posterior limb mesenchyme (arrowheads). (F) Stage 25, Tbx3 is present in the limbs in two stripes in the anterior and posterior limb mesenchyme (arrowheads). (G) Schematic diagrams of Tbx3 constructs. (H) Bar chart representing the relative luciferase activity obtained in luciferase assays with Tbx3 constructs. S, somite; LP, lateral plate mesoderm; V, ventral lip of dermomyotome; M, mesoderm; E, ectoderm.