Dorsal longitudinal muscle a (DLMa) is innervated by a single motor neuron that has, on average, 5 contact points with the muscle in both wild type and Fas2^e93 mutants.

Fas2^e76/Fas2^e93 transheterozygotes exhibit a 50% increase in number of MN boutons at muscle 6. Mild heat induced expression of CrebB-17A^a.hs during larval stages significantly increases the quantal content of the synapse without altering quantal size (as shown by measuring excitatory postsynaptic potential, EPSP). Homozygotes have a wild type bouton number, mild heat induced expression of CrebB-17A^a.hs during larval stages does not alter synaptic strength.

In homozygous embryos the SNb fails to diverge from the ISN partially (partial bypass) in 3% segments. Fas2^e93; beat-Ia² flies have a strong beat-Ia phenotype, 90% segments have a divergence defect.

In Fas2^e76/Fas2^e93 transheterozygotes growth of the synapse increases as Fas2 expression level is low causing a rise in number of boutons.