Hemizygous third instar larvae have large gaps in the lamina with numerous abnormal thick axon bundles projecting into the medulla. Many mistargeted R2-R5 axons project into the medulla. This phenotype is 100% penetrant. The morphology of the R8 growth cones is abnormal.
Homozygous R8 axon MARCM clones show severe targeting defects, failing to stay in their appropriate target zones and straying into neighbouring regions. Homozygous R2-R5 axon MARCM clones show appropriate targeting to the lamina region.