Three phenotypes of Dally mutants. The top two panels show third instar larval brains stained with anti–Cyclin B antibody to reveal patterns of cell division (anterior to the left, dorsal up). The wild-type displays two bands of dividing cells that generate components of the visual system. One of these two sets of dividing cells is absent in dally mutants (arrows). The middle panels show scanning electron micrographs of a wild-type and an abnormal eye of a dpp/+; dally/+ transheterozygote. Both dpp and dally mutations are completely recessive, and the eye defects found in animals heterozygous for both mutations reveal a functional link between Dally, a Drosophila glypican, and decapentaplegic (Dpp), a homolog of bone morphogenetic protein 4. The bottom row shows wing margin notching and incomplete wing vein formation (arrowheads) associated with dally mutations. These defects are likely the result of defects in Wingless (a Wnt) and Dpp signaling, respectively.