The septate junctions of the peripheral glia are fewer, thinner and less regularly spaced than normal in mutant stage 17 embryos. Septate junctions in the glial cover of the central nervous system are also disrupted. Neuronal fibres in the neuropil of the central nervous system are significantly enlarged compared to wild type. The taenidia, which normally reinforce the cuticular lining of the largest tracheal trunks are also disorganised.

After 18 hours of development, homozygous embryos twitch in a random and uncontrolled fashion, moving far more frequently than heterozygous controls, but no patterned contraction is seen. The hyperactivity gradually disappears and the mutant embryos become immobile by the end of embryogenesis.