Stage 16 mutant embryos show defects in wrapping of nerves by glia; close to the central nervous system, wrapping of axons by the glia is almost complete, but no clear morphological distinction can be made between the perineurial and the inner glial cell layer. In areas with glial membrane-membrane contact, no signs of septate junction formation can be detected. In more dorsal sections, only very thin glial processes can be detected that do not properly grow around the neuronal fascicles and many axonal profiles are not in contact with any glial cell process.

Epidermal thoracic domain T1 cells enter a normal S17 and M17 during division 17 in mutant embryos. The number of mitotic cells in the brain lobes of mutant stage 16-17 embryos is the same as in wild-type embryos at this stage.