Fig. 4. Wg acts antagonistically to L. Loss of L (L²/+) results in preferential elimination of the ventral eye cells, as seen in eye disc (A), adult eye (B) and adult eye sections (C,C'). The loss-of-ventral-eye phenotype of L²/+ mutants is restored in the wg-mutant background (L², wg¹/CyO), as seen in the eye disc (D) and adult eye (E). Sections of L², wg¹/+ fly eye show restoration of the ventral eye-specific ommatidia (F,F'). In C' and F', circles represent ommatidia with uncertain polarity, and blue and red arrows indicate dorsal and ventral polarity, respectively. In third instar eye disc, wg-lacZ is strongly expressed on both dorsal and ventral polar margins (Royet and Finkelstein, 1997). (G) In the L²/+-mutant background, wg-lacZ is ectopically induced on the ventral posterior margin of the eye. (H-I') LOF clones of L^rev, marked by loss of the GFP reporter, in the ventral eye show ectopic induction of Wg (arrow). The size of the ventral eye is smaller, suggesting that some of the ventral eye cells are lost. There is no effect on Wg in LOF clones of L in the dorsal eye (marked by dashed line, arrowhead).