Fig. 1. Loss of ventral eye in L mutants. (A,B) Wild-type and L^si homozygote adult eyes by scanning electron microscopy. (C,D) Wild-type and L^si third instar eye discs. The morphogenetic furrow and photoreceptor clusters were respectively marked with dpp-lacZ reporter staining (blue) and neural marker Elav (brown). Furrow progression and Elav expression were normal within the remaining eye disc. (E) mirr-lacZ enhancer trap line, mirr^B1-12. (F) w^–; L^si; mirr^B1-12/+ flies have mostly w⁺ ommatidia. (G) Wild-type, second instar eye disc stained with anti-ß-gal to label mirr-lacZ⁺ dorsal cells (brown). (H) In L^si second instar eye disc, mirr-lacZ⁺ dorsal domain is considerably larger than the ventral domain (outlined by the broken line). (I) L^– mosaic eyes disc generated with L^rev6-3 allele. Clones were visualized by the absence of the lacZ marker (red). Ventral, but not dorsal domain of the eye disc was greatly reduced. A cell junction marker, Dlg (green), was used to outline cells in the disc. (J) Adult mosaic eye showed intact dorsal eye and cuticle-replaced ventral eye. In all figures, white lines mark the DV boundary and broken lines mark the putative ventral domain. Dorsal is upwards and anterior towards the right.