Dscam³³ posterior Dorsocentral (pDc), anterior Scutellar (aSc) and posterior Scutellar (pSc) neuron clones enter the thoracic ganglion at the correct position but are unable to correctly target axonal branches and fail to elaborate any arbors. These neurons are able to form axonal branches but these remain clustered in a small bolus around a presumptive decision point. This phenotype is 100% penetrant for all tested neuron clones.

The overall innervation pattern of Dscam³³ mutant antennal olfactory receptor neurons through the antennal nerve into the antennal lobe is largely normal. Dscam³³ mutant maxillary palp olfactory receptor neurons that project into the central nervous system along the labial nerve frequently terminate not within the antennal lobe but in regions surrounding it and the suboesophageal ganglion. Or47a-expressing olfactory receptor neurons (ORNs) that are mutant for Dscam³³ show marked mis-targeting of axons in the antennal lobe, often failing to project to the normal target (glomerulus DM3) and instead innervating abnormal locations on the ipsilateral side. less frequently, targeting to ectopic or cognate sites in the contralateral lobe is seen. P{GAL4}GH298-expressing ORNs that are mutant for Dscam³³ often fail to project to their normal target (the V glomerulus), innervating abnormal locations on the ipsilateral side. Single Dscam³³ mutant Or47a-expressing ORNs exit the antennal nerve and often terminate in abnormal locations between glomeruli. Mutant terminals that do reach the appropriate glomerulus fail to elaborate the network of thin arbors characteristic of wild-type terminals. Or22a-expressing and Or23a-expressing Dscam³³ mutant ORNs target normally to the correct glomerulus, although they show a marked reduction in branches to the contralateral antennal lobe. Or47b-expressing Dscam³³ mutant ORNs show mistargeting to more dorsal regions of the antennal lobe than the normal target (the VA1 l/m glomerulus) and also targeting defects in the contralateral lobe. Or46a-expressing and Or59c-expressing Dscam³³ mutant ORNs frequently terminate upon entering the ventral central nervous system before reaching the antennal lobe, either immediately prior to entering the suboesophageal ganglion or upon exiting it, just ventral to the antennal lobe. Or71a-expressing Dscam³³ mutant ORNs frequently terminate upon entering the ventral central nervous system before reaching the antennal lobe, either immediately prior to entering the suboesophageal ganglion or upon exiting it, just ventral to the antennal lobe. The mutant ORNs form a structure with the appearance of a glomerulus where they terminate.