The overall organisation and branching pattern of the embryonic tracheal system is unaffected in bou^6Ea-2 homozygous and bou^6Ea-2/bou^PG27 trans-heterozygous mutants. However, both the shape and the length of the tracheal dorsal trunk segments are abnormal in mutant flies. Differing from the wild-type, this structure appears in stage 15 embryos as a succession of bulging cysts and, by stage 16, as an abnormally convoluted tube. The fibrous structure of the tracheal chitin cable is disorganised in mutant embryos and chitin is deposited as an amorphous material in the tracheal lumen.

At stage 16, the dorsal trunk of the tracheal system is enlarged in the mutant embryos compared to wild type and has a convoluted shape. At stage 15, the dorsal trunk of is not a uniform width but appears as a series of bulging cysts. The luminal chitin cable is disorganised in the mutant trachea.

The paracellular barrier function of the mutant trachea is disrupted; dextran dye is readily detected within the tracheal tubes within 20 minutes of injection of the dye into the body cavity of mutant embryos. In addition, dextran diffuses into the chordotonal organ lumen after injection in the mutant embryos, but not in wild-type embryos. The paracellular barrier function of the central nervous system is intact in the mutant embryos.

bou^6Ea-2 animals which are expressing bou^{Scer\UAS.T:Ivir\HA1} under the control of Scer\GAL4^nullo.PG (to bypass the embryonic lethality of bou^6Ea-2) die at pupariation and have discs with a reduced size and abnormal shape.

Shows no maternal effect in homozygous germ-line clones.