<i>Bmp4</i> mRNA expression is displaced in <i>Gli3^xt/xt</i> embryos.

<p>Whole-mount <i>in situ</i> hybridization for <i>Bmp4</i> in wt (A, B) and <i>Gli3^xt/xt</i> (D, E) embryos. In 40-somite stage wt embryos (A) <i>Bmp4</i> is expressed ventrally. This expression is more intense in <i>Gli3^xt/xt</i> embryos at this stage (D). At the 45-somite stage, expression is reduced in wt embryos (B arrow), but expression is displaced dorsally and centrally into the locale of the developing mammary placode #3 in <i>Gli3^xt/xt</i> embryos (E arrow). Distance from the axilla to the most distal point of <i>Bmp4</i> expression (B, E white dotted lines) was measured in mm. Sections through a 45-somite wt embryo (C) and higher power (C’) show mesenchymal expression ventral to the developing placode #3 (arrow). Sections through a 45-somite <i>Gli3^xt/xt</i> embryo (F) and higher power (F’) show the displaced <i>Bmp4</i> expression. Control <i>in situ</i> hybridization with <i>Bmp4</i> sense probe is shown on a wt embryo in (G). Abbreviations: F – fore-limb, H – hind-limb, nt – neural tube, s – somite.