Figure 3.—

Loss of Polycomb and osa function disrupt eye development. (A) Wild-type eye-antennal imaginal disc labeled with anti-Elav. Differentiating photoreceptor cells (brown) are confined to the posterior half of the eye disc, behind the morphogenetic furrow (indicated by arrowheads). (B and C) Eye imaginal discs with mutant osa³⁰⁸ and Pc^XT109 cell clones were stained with anti-GFP to identify the position of the clones (absence of green GFP signal indicated by dotted lines) and anti-Elav (red) to mark differentiating photoreceptor cells. (B) No photoreceptor cells are specified within a large Pc clone. (C) A large osa clone disrupts the regular spacing of the photoreceptor clusters even outside the clone (arrowheads), indicating a cell-nonautonomous function.