Fig. 5. The Hh pathway, omb and polarity. (A) A clone that lacks both ptc and omb marked with singed. The clone makes a6 cuticle like ptc^– clones, but reverses polarity in the front half of the clone as do omb^– clones in this position (see Fig. 2, Fig. 5B) and unlike ptc^– clones (Lawrence et al., 1999a). (B) A comparison between ptc^– and omb^– ptc^– clones, they both affect the scalar in the same way, making a6 cuticle; but they have very different effects on polarity. (C) A clone of cells, marked with pawn that overexpresses a form of Ptc that blocks Hh reception but not Hh movement. All the pawn cells with A provenance form pigmented (a3) cuticle. The polarity is largely reversed, even at the back of the clone and in some places, behind it. To the left there is a small clone of P provenance.