At 30-36 hours after puparium formation in Nlg1^I960/Df(3R)BSC747 flies, persistent motor neurons which innervate the abdominal lateral tergosternal muscles have more tortuous axonal branches, but similarly dynamic filopodia compared to wild-type controls. In late pharate adults, axons display significantly reduced total arbor length and area of arbor coverage, but no differences between total branch numbers and arbor complexity compared to wild-type controls. Additionally, there is no difference in synaptic density in motor neuron axons in the adult.

Mutants have smaller neuromuscular junctions than normal. The percentage of non-growing branches at the neuromuscular junction is increased compared to controls at both the first and third larval instar stages.

The neuromuscular junctions of Nlg1^H324/Nlg1^I960 and Nlg1^ex2.3/Nlg1^I960 larvae are smaller than normal. The average bouton number per muscle area and average number of boutons normalized to synaptic branch length are significantly reduced, and the average diameter of the largest bouton at a given neuromuscular junction is slightly but significantly increased in homozygous, Nlg1^I960/Nlg1^H324, Nlg1^I960/Df(3R)dsx29 and Nlg1^I960/Nlg1^ex2.3 mutants.

Ultrastructurally, presynaptic active zones are still formed in Nlg1^H324/Nlg1^I960 mutant boutons. The mutant active zones contain T-bars and clustered synaptic vesicles. The synaptic vesicles are present at approximately normal size and density, with large vesicle diameters in slightly higher numbers than normal. A subset of the mutant boutons show a reduction in thickness of the subsynaptic reticulum (SSR). The relative SSR area is significantly reduced in the mutant boutons compared to controls, and in extreme cases, boutons appear to be in "direct contact" with the contractile muscle filaments without being surrounded by SSR. Active zones are still present at locations lacking SSR and maintain the tight apposition of presynaptic and postsynaptic membranes. The number of membrane ruffles in active zones is strongly increased in the mutants, while the distance of these ruffles to the centre of the T-bar is unchanged.

The mean amplitude of the evoked excitatory junctional current (EJC) from neuromuscular junctions of Nlg1^H324/Nlg1^I960 third instar larvae is significantly reduced compared to controls at both 0.5mM and 1mM extracellular Ca[2+]. The mean amplitude of spontaneous miniature EJCs at the mutant neuromuscular junction is unchanged relative to wild type.