Figure 3. SU5402 alters gene expression patterns in the FEZ.

(A) At 48 hrs after application of DMSO-soaked beads, Fgf8 transcripts were detected in the optic recess (OR), the anterior telencephalon (arrowhead), and the FEZ (arrow) of control embryos (n=6). (B) At this time embryos treated with SU5402 expressed Fgf8 in the anterior forebrain and FEZ, but the domain of expression in the optic recess was absent (n=8). (C) In control embryos at 72 hrs after treatment Fgf8 expression remained in the optic recess and anterior telencephalon but was absent from the midline of the FEZ (n=6). (D) After treatment with SU5402 the Fgf8 domain in |FEZ was still present and this domain (arrow) and the domain of expression in the forebrain (arrowhead) were shifted proximally (n=8). (E) In control embryos at 48 hrs (HH 19/20) after bead implantation Shh transcripts were detected in the diencephalon (Di), telencephalon (Te) and the FEZ (arrow; n=6), (F) but in treated embryos a small domain of Shh was detected in the brain (arrowhead; n=12). (G, I) At 72 hours (HH 23/24) Shh expression had expanded to include all the ectoderm encasing the roof of the mouth (arrow; n=5). (H, J) However, in embryos treated with SU5402 Shh expression in the brain was disrupted. In the surface ectoderm, the Shh domain (arrow) was only apparent in regions that were adjacent to neural crest mesenchyme (dotted line; n=8). (K) Normally, at 96 hrs after bead implantation, Shh expression extended across the mediolateral axis of the FNP during outgrowth of the upper jaw (n=6). (L) However, at this time in embryos treated with SU5402 the FEZ was split into two and Shh expression was apparent in lateral domains of the FNP (n=10). Scale bars: A–H: 500μm, I–L: 1mm.