Figure 1.

Expression of Bmp4 and BMP type 1 receptor genes during kidney and urinary tract development. Two adjacent sections from E10.5 (a, b, and g–j), E12.5 (c, d, and k–n) and E14.5 (e and f) embryos were processed for (left) H&E staining and (right) in situ hybridization of Bmp4 (b, d, and f), Alk3 (h and l), or Alk6 (j and n). (a and b) Bmp4 is expressed in the mesenchymal cells surrounding the WD (arrowheads), but not in MM and WD per se. (c and d) Bmp4 expression is seen around the branching ureter and ureter stalk, but not in the MM. (e and f) In addition to the expression in the stromal mesenchyme, Bmp4 mRNA is distributed in the S-shaped bodies (arrowheads) and the prospective smooth muscle layer along the ureter. (g, h, k, and l) Expression of Alk3 is essentially ubiquitous, but noticeably intense in WD and the branching ureter (arrowheads in h and l). (i, j, m, and n) Alk6 transcripts are exclusively present in the WD and the ureter epithelium (arrowheads in j and n). WD, Wolffian duct; MM, metanephric mesenchyme; Ut, ureter; BUt, branching ureter within the kidney. Bar, 200 μm.