Unlike wild-type, post stage 15 trachea in nrv2^k04223 homozygotes are unable to exclude from their lumens, a fluorescently labelled 10kDa dextran injected into the body cavity. This is consistent with these trachea lacking a functioning septate junction barrier.

Mutation has no obvious effect on the morphology of the salivary gland or hindgut. Early tracheal development, including primary branch budding and outgrowth and lumen formation and morphology occur normally during stages 11-14. Stage 16 embryos show a number of tracheal defects. These include an increased length of the dorsal trunk compared to wild type (with no accompanying increase in cell number), mild defects in the diameter of the dorsal trunk and moderate defects in the diameter of other primary branches. Irregular and variable tracheal tube morphologies, with local constrictions and/or dilations are seen in all major branches. The defects are first seen at stage 15.