Fig. 3. Providing Fz locally to fz^– territory. en.Gal4 driving UAS.fz in fz^– flies provides a band of Fz expression in the P compartment (genotype 8). This appears to have two effects: 1. The interface at the front causes a reversal of polarity around that interface that extends one cell into the fz^– territory but more cells into the P compartment. 2. The remainder of the P compartment is rescued, with the rescue extending one cell into the fz^– territory behind. Overall, we see a band of order imposed on the disorder seen in the majority of the A compartment. The detail on the right shows the two zones of organised polarity and our estimate of where the P compartment is (estimated from clones, and from other experiments where UAS.fz is driven by hh.Gal4 in flies carrying ptc.lacZ).