Kidney morphogenesis progresses well in FiZD culture. Embryonic kidneys (A,D-G) and organoids (B,C,H) were grown in FiZD culture. (A) Brightfield micrograph of an intact embryonic kidney, and (B) kidney organoid cultured for 7 days. (C) Snapshot of the time-lapse image stack depicting Wnt4Cre-activated GFP expression in the assembling nephrons on the fourth day of FiZD culture. (D) Six2 and Troma-I (Krt8) staining highlight nephron precursors and UB bifurcations, respectively, in a 7-day FiZD culture. (E) Kidney rudiment FiZD-cultured for 12 days. Troma-I and Nephrin staining depict the UB bifurcations and podocytes, respectively. (F) High-power magnification of the Nephrin+ podocytes and Troma-I+ UB in E. (G) Frame from the time-lapse image stack of Flk-GFP endothelial cells. Henle's loop-like structures (arrowheads). (H) Umod+ loops of Henle (arrowheads) in an organoid cultured for 7 days. Umod and Hoechst stainings. Scale bars: 100 µm in A-D,F-H; 1000 µm in E.