The axon terminal defects of gft8 are observed in mutant neuroblast clones, as well as in single-cell/two-cell clones of mutant γ neurons. Mutant neuroblast clones acquire shorter γ and β' lobes than wild-type clones. Most γ processes in the mutant neuroblast clones are only approximately two-thirds the length of wild-type γ processes. In contrast to the truncated γ and β' lobes, only subtle morphological defects are observed in the α, α', and β lobes. These three lobes extend as far as their wild-type counterparts, but their tips are rougher and less dense. Approximately 76% of single-cell/two-cell clones of mutant γ neurons, unlike their wild-type controls, fail to project axons to the tips of the γ lobes.
In wandering larvae, gft8 mutant clones acquire larval mushroom body-specific morphological features, including two perpendicularly oriented lobes, as well as two short bundles of terminal branches. No dramatic morphogenetic defects are observed in gft8 mutant clones at this stage, except subtle deformation of the termini of the medial axon bundles.
By 18 hours after puparium formation, most larval-specific axonal branches are pruned in gft8 mutant clones and look morphologically indistinguishable from their wild-type controls. In contrast to normal pruning, severe regeneration problems in gft8 mutant clones are observed. For instance, by 48 hours after puparium formation, regrowth of the majority of mutant axons is incomplete and appears unsynchronised. No age-dependent morphological changes are detected in gft8 clones after eclosion.
gft8 mutant γ axon clones exhibit few arbors. Approximately 57% of fully extended mutant γ neurons have no major (defined as over 15υm) axon arbors (compared to 15% in wild-type), suggesting that arborization is suppressed in mutant γ axons. However, a similar percentage of γ neurons (14% in mutant, 15% in wild-type) acquire fully extended 'arbor-free' axons, regardless of the size of arbor.
gft8 single cell mutant γ processes can terminate within any part of the γ lobes.
gft8 single cell mutant neuroblast clones exhibit a subtle phenotype in the α lobes.
Truncation occurs in 25% of gft8 β processes. All truncated β axons stall within either the proximal one-third segments or the distal one-third segments of the β lobes, close to the positions at which two clusters of arbors form in wild-type β processes.