Fig. 7. Pleiotrophin expression in the embryonic kidney. (A) Immunoblot detection of pleiotrophin. Lane 1, extract of whole E13 rat kidney; lane 2, conditioned medium collected from UB cells; lane 3, conditioned medium from BSN cells. Whole kidney and BSN-CM were positive for pleiotrophin (arrowheads). (B) Frozen sections of E13 mouse kidney stained with anti-pleiotrophin antibody. Pleiotrophin is present at the basement membrane of developing UB (a). Treatment with normal goat IgG did not result in significant staining (b). Scale bar, 100 µm.