Fig. 3.

COUP-TFII specifically regulates the metanephric mesenchyme gene expression. Tamoxifen was administered at E8.5 to delete COUP-TFII. Transverse sections of the metanephric mesenchyme region from the embryos were stained with Hematoxylin and Eosin at E10.5. (A,B) The condensed metanephric mesenchyme (mm) was seen in both the COUP-TFII^f/f control (A) and the COUP-TFII^d/d mutant (B) embryos. (C-H) At E10.5, the metanephric mesenchyme of COUP-TFII^d/d mutant embryos expresses Eya1 (D), Wt1 (F) and Six2 (H); however, the expression levels per cell of all of these three factors are lower than control (C,E,G). Eya1 expression level was measured by in situ hybridization (C,D). The DAPI counterstain for nuclei (blue) was applied in E-H. (I-L) lacZ staining indicates that COUP-TFII is deleted in the mesenchyme cells and is specifically colocalized with Six2 in that area of COUP-TFII^d/d mutant (I,J). J shows a high magnification of the dashed box in I. Arrows indicate that cells that express higher Six2 levels have lower lacZ expression (L) and arrowheads indicate that cells that express higher lacZ have lower Six2 expression (K). (M) The Six2 expression level of Six2-positive cells was measured by the fluorescence density divided by area (densitometric mean) from COUP-TFII^f/f control and COUP-TFII^d/d mutant embryos. Four metanephric mesenchyme samples were measured and the results indicate that COUP-TFII deletion in the metanephric mesenchyme significantly reduces Six2 expression. ^**P<0.005. ur, urogenital ridge; wd, Wolffian duct. Scale bars: 50 μm.