Fig. 4. Renal branching morphogenesis is reduced in kidneys from E13.5 TgALK3^QD/QD embryos. (A) Ureteric bud branching in TgALK3^QD/QD versus control kidneys. Left: DBA-stained whole-mount preparations of E13.5 kidneys. Ureteric bud branches are highlighted. Right: quantitation of branch points demonstrated 36% fewer branches in TgALK3^QD/QD versus control kidneys. (B) Ureteric bud cell proliferation in TgALK3^QD/QD versus control kidneys. Left: Hematoxylin-stained E13.5 kidney tissue. BrdU incorporation is identified by HRP-conjugated mouse anti-BrdU antibody yielding red colored cell nuclei. Note the marked reduction of BrdU uptake in the ureteric bud (UB) of TgALK3^QD/QD mice. By contrast, BrdU in glomerular progenitors and mesenchymal cells is similar in TgALK3^QD/QD and control kidney sections. Right: quantitation of the percentage of BrdU-positive ureteric bud cells demonstrated a 60% reduction in TgALK3^QD/QD versus control mice. Data are mean±s.d from three separate experiments.