Fig. 8. The Expression of Otk in R7 did not retarget R7 growth cones to the lamina. Otk was expressed in R7 (B) under control of the PM181-GAL4 driver. Third-instar eye–brain complexes were stained with anti-ß-galactosidase. Individuals in A and B carried the PM181-GAL4 driver and an UAS-lacZ transgene. Individuals in B also carried an UAS-otk transgene. In an individual expressing Otk in R7 axons (B), like that in wild type (A), all labeled R7 axons projected correctly through the lamina (la) into the medulla (me). Scale bar: 20 µm.