The dishevelled gene of Drosophila is required to establish coherent arrays of 
polarized cells and is also required to establish segments in the embryo. Here, 
we show that loss of dishevelled function in clones, in double heterozygotes 
with wingless mutants and in flies bearing a weak dishevelled transgene leads to 
patterning defects which phenocopy defects observed in wingless mutants alone. 
Further, polarized cells in all body segments require dishevelled function to 
establish planar cell polarity, and some wingless alleles and dishevelled; 
wingless double heterozygotes exhibit bristle polarity defects identical to 
those seen in dishevelled alone. The requirement for dishevelled in establishing 
polarity in cell autonomous. The dishevelled gene encodes a novel intracellular 
protein that shares an amino acid motif with several other proteins that are 
found associated with cell junctions. Clonal analysis of dishevelled in leg 
discs provides a unique opportunity to test the hypothesis that the wingless 
dishevelled interaction species at least one of the circumferential positional 
values predicted by the polar coordinate model. We propose that dishevelled 
encodes an intracellular protein required to respond to a wingless signal and 
that this interaction is essential for establishing both cell polarity and cell 
identity.