We examined expression of three Wnt genes in Pygo mutants. Wnt7b is expressed in the stalks [20], Wnt11 in the tips [4], and Wnt9b in the stalks and weakly in the tips of the branching ureteric bud [2]. All three genes showed similar expression patterns in Pygo2+/+ and Pygo1/Pygo2 double-mutant kidneys (Figure 4). In addition, these in situ hybridization patterns confirmed the confocal microscopy results, showing a reduced number of tips (Wnt11-positive) per surface area in the Pygo1/Pygo2 double-homozygous mutants.