Fig. 4. Fine mapping of the gbb focus in the anterior compartment. Dark field photomicrographs of wings bearing double-sided gbb null clones (dark patches). Clones falling between the anterior margin (L1) and L3 (A,B) have no effect on L5 or overall wing size. Similarly, clones entirely contained within L3 and L4 are wild type (E). Effects on wing size and L5 specification are observed in clones that occupy the entire anterior compartment (C) or all of the region between the L2/L3 intervein and L4 (D).