Fig. 4. Clones involving prickle (pk). (A) Part of the pleura of a fly lacking pk and stained for hh.lacZ to demarcate the P compartments (genotype 11). Note the alternating zones of polarity, with much of the back half of the A compartment having reversed hairs (red arrows). (B,B') Uniform overexpression of sple gives zones of reversed polarity coinciding more or less with the P compartments (genotype 12). P compartments of the first and second abdominal segments are shown, with a magnified view of part of the second (B'). Anterior to left. (C) A clone lacking pk (marked with shavenoid which removes most of the hairs). The hair orientation within the clone is whorly (genotype 24). (D) A clone expressing sple in the P compartment. Most of the cells in the clone, and some cells behind, have reversed polarity. The front of the clone displays normal polarity (genotype 25). (E) Two clones lacking fz, marked with tricornered in a pk^– fly (genotype 19). Note that, in spite of the varying zones of polarity in the background, the hairs point consistently into the clones. Phase image, clone outlines were ratified in a DIC image (not shown). (F-H) Expressing fz in the P compartment causes a zone of reversed polarity across the A/P border of wild type (F, genotype 9) and also pk^– flies (G, genotype 20). Note that in pk^– flies polarity is normal in that region (H, genotype 21).