At the end of embryogenesis, kkv^DZ8 mutant embryos exhibit severe tube dilations and cysts in all multicellular branches of the tracheal system. In addition, the ganglionic branches show discontinuities at the borders of the ventral nerve cord. However, branching of the tracheal system appears normal.

Homozygous embryos fail to hatch but are initially hyperactive, often reversing themselves within the eggshell (7.8% of embryos show this "retroactive" phenotype). When the embryos are mechanically devitellinised the resulting cuticle preparations stretch to a much greater extent than wild-type cuticles, resulting in inflated cuticles ("blimp" phenotype). Embryos have defects in the head skeleton and slight denticle belt abnormalities.