Figure 4.

Hoxd11/lacZ gene expression in HoxD deletions. (Left to right) TgH[d11/lac]^Ge, Del3, Del7, and Del9 embryos. (A–D) In E9 embryos, the TgH[d11/lac]^Ge locus was expressed around the proctodeum (A), like the neighboring Hoxd13 gene. The Del3 allele showed a more anterior domain, mimicking Hoxd11 (B). The brackets emphasize the absence of staining in limb buds. In the right two panels (C,D), the Del7 and Del9 alleles showed expression profiles expanded anteriorly, involving the forelimb buds. (E–H) In E11 embryos, the TgH[d11/lac]^Ge locus (E) showed the most posterior expression. In the trunk, the anterior limit was located at pre-vertebra 27, the future lumbo–sacral transition (black arrowhead in E–H). Blue arrowheads indicate expression in digit primordia. In Del3 embryos, the limit of expression was at pre-vertebra 25 (F). Expression in hernial gut (F, red arrowhead) was maintained in the other configurations to the right (G–H). In Del7 embryos, the anterior limit of expression in the central nervous system was reminiscent of Hoxd3 (G). In Del9 embryos, few cells only showed expression in either paraxial mesoderm or spinal cord (H). The strong staining in cervical pre-vertebrae detected from the Del7 locus was lost. In ventral regions such as the hyoid, rib primordia, and ventral tail mesoderm, expression was seen as anterior as the first branchial arch. Expression in both the digit primordia and hernial gut were preserved in the absence of the HoxD cluster (H).