Fig. 6. Lineage analysis of Bmp7^cre/+;Smad^–/CA kidneys. The ROSA26^R reporter was introduced into the Bmp7^cre/+(WT) and Bmp7^cre/+;Smad4^–/CA (Mut) backgrounds. At E11.5, the ureteric bud and condensing mesenchyme of wild-type (A) and mutant (B) kidneys are labeled by lacZ expression. At E12.0 (C,E), all cells within the nephrogenic mesenchyme of wild-type kidneys are labeled, whereas there is significant mixing of labeled and unlabeled cells in the mutant (D,F). Labeled and unlabeled cells are distributed throughout the mesenchyme of mutant kidneys. At E14.5, nephrogenic mesenchyme is labeled in wild-type kidneys (G), and the stroma surrounding mesenchymal condensates is unlabeled. In mutant kidneys (H), the limited nephrogenic mesenchyme that can be seen is labeled, and there is a disorganized distribution of labeled cells throughout the cortical layer, which is composed of a mixture of labeled and unlabeled cells. At E16.5, nephrogenic mesenchyme is labeled, and unlabeled stromal cells are more obvious in wild-type kidneys (I). In mutant kidneys, a few remaining labeled cells lie within the otherwise unlabeled cortical layer (J). Ectopically placed glomeruli are prominent. CD, collecting duct; G, glomerulus; NM, nephrogenic mesenchyme; PS, peripheral stroma; UB, ureteric bud.