dock13421/+ mutant third instar larval eye discs do not show disrupted axon targeting from photoreceptor neurons to the brain optic lobes.
When mutant clones are made in the developing eye, no R-cell precursor nuclear migration phenotype was seen.
Photoreceptor cell axons fail to target the optic lobe properly in mutant larvae; crossing of axons, gaps in the lamina and blunt ended termination point in the medulla are seen.
The growth of retinula axons into the brain is disrupted in homozygous larvae, leading to a disruption of the lamina neuropile organisation. Homozygous embryos show a reduction in the longitudinal connectives and a slight fusion of the segmental commissures. The VUM neurons do not project normally.
In dock04723/dock13421 embryos, either the entire Bolwig's Nerve, or a subset of its axons project to ectopic positions. These defects have over a 90% penetrance.
In dock13421/dock3 mutant embryos longitudinal connectives are more wavy and more varied in thickness than wild type and the outermost one is occasionally interrupted. There are low penetrance defects in muscle organization. The muscle phenotype is not affected further in embryos lacking both maternal and zygotic dock activity. dock13421/dock3 mutant embryos (and homozygotes of both alleles) show a variable absence of the synapse between RP3 and muscles 7 and 6. Outgrowth of RP3 from the CNS is normal. Synapse formation eventually occurs, but is delayed. No ectopic synapses occur. This phenotype is identical to that of lbmY13. Maternal loss of dock expression enhances the CNS longitudinal axon defects, but not the RP3 synapse formation delay.
Some homozygotes survive to adulthood. These flies are sluggish and uncoordinated, dying within a few days after eclosion. Homozygous third instar larvae exhibit defects in receptor cell fasciculation, targeting and retinotopy. Receptor cell axons terminate at different depths in the developing lamina and form clumps of terminals instead of an even array. Bundles project from these regions into the medulla. Some bundles project along abnormal paths.