Mutant embryos have alterations in embryonic morphology. No epidermal folds are found below the ventral nerve cord. Instead of stretching dorsally, the ectoderm appears to fold like an accordion in the anterior-posterior axis. As a consequence the gut is frequently pushed outside the embryo. By the end of embryogenesis the ventral folding of the epidermis pushes the ventral nerve cord further deep into the embryo. Beside the dorsal closure phenotypes, defects are also seen during head involution and in gut morphology. Mutant embryos also typically have fused commissure phenotypes where anterior and posterior commissures are not separated. Longitudinal connectives are also often reduced and frequent gaps may be seen in tracts. Glial cell organisation is severely affected in mutants. Mutants have a significant increase in the number of midline glial cells. About 6 cells are seen per neuromere.

Cuticle and head structures are undifferentiated in dib^unspecified mutant embryos.