Figure 1. A) Somites (arrows) of mutant embryos at 9.5 days of gestation display no Fgf8 expression. B) Kidneys of mutant neonates are hypoplastic and nonfunctional. C) A ring of aberrant cell death (red) occurs in mutant kidneys at 14.5 days of gestation, where nephrogenesis would normally be taking place. D) Data from mutant analysis and in vitro explant experiments were used to generate a model wherein FGF8 induces Wnt4 gene expression and then both FGF8 and WNT4 are required for Lim1 gene expression and nephrogenesis. ad, adrenal gland; bl, bladder; ki, kidney; ov, ovary; ur, ureter; ut, uterus.