Figure 7.

Immunofluorescent staining of Six2 in wild type and Br/Br embryos. Six2 staining is shown in green, while nuclei stained with propidium iodide are in red, and areas of overlapping signal are shown as yellow. Six2 only localized in cell nuclei as expected for a transcription factor. In wild type E11.5 heads (A, C), Six2 was localized primarily in the MNP and midline mesenchyme, extending dorsally into the developing chondrocranium. Six2 was also localized to the olfactory epithelium of the nasal pits. In Br/Br embryos, Six2 staining was not detected in any of these tissues (B, D). At E11.5, the UB has begun to branch into the MM, and Six2 staining in wild type embryos was strong in the MM surrounding the UB tubule (E). In the Br/Br E11.5 kidneys, Six2 was not detected (F). In the E14.5 wild type kidney, Six2 was localized around the periphery of the developing kidney in the undifferentiated MM cells (G), while Six2 staining in the disorganized Br/Br E14.5 kidneys is absent (H). LNP = lateral nasal prominence; MNP = medial nasal prominence; OE = olfactory epithelium.