Fig. 3. Morphology of Bmp7^cre/+;Smad4^–/CA and HoxB7cre;Smad4^–/CA kidneys. (A-C) Sagittal sections of E16.5 kidneys. (A'-C') High magnification images of the cortical zone of each section. Kidneys of HoxB7cre;Smad4^–/CA (H7.S4) kidneys (B) are indistinguishable from wild type (A). Bmp7^cre/+;Smad4^–/CA (B7.S4) kidneys (C) display hydroureter and cyst formation. Nephrogenic mesenchyme is missing from the majority of collecting duct tips, and the cortical cell layer is thickened (bracket in C'). E14.5 Bmp7^cre/+;Smad4^–/CA kidneys (E) are smaller than wild-type controls (D) and display a prominent thickening of the cortical layer normally composed of nephrogenic mesenchyme and peripheral stroma (arrow). E12.5 Bmp7^cre/+;Smad4^–/CA kidneys (G) are of comparable size to wild-type controls (F). CD, collecting duct; C, cyst; G, glomerulus; NM, nephrogenic mesenchyme; T, tubules.