Fig. 5. Pleiotrophin-mediated UB branching morphogenesis is concentration dependent. (A) Phase contrast photomicrographs of isolated ureteric buds grown for 7 days in DMEM/F12 supplemented with increasing concentration of purified pleiotrophin. In each case, the growth medium was also supplemented with 10% FCS, 125 ng/ml GDNF and 250 ng/ml FGF1. The numbers in the upper-left-hand corner of each picture indicate the concentration of pleiotrophin in µg/ml. Clear differences in the phenotype depending on the concentration of pleiotrophin are exhibited. (B) Phase contrast photomicrographs of isolated ureteric buds grown for 11 days in the absence or presence of 250 ng/ml FGF1 diluted in DMEM/F12 supplemented with 2.5-5 µg/ml pleiotrophin (PTN), 10% FCS, and 125 ng/ml GDNF. Scale bar, 500 µm.