Ubiquitous over expression of vnd in vnd^hs.PM embryos yields an extreme CNS phenotype. The longitudinal fascicles are reduced to clumps of neurons that make minimal contact with one another and are found at irregular distances, too far from the midline. The commissures generally do not form. EL neurons are usually missing in vnd^hs.PM mutants. In vnd^hs.PM mutants there are increased levels of futsch expressing neurons in the anterior of the hemisegment, at the expense of futsch-positive posterior hemisegment neurons. In vnd^hs.PM embryos clumps of neurons are detected in an antero-midline proximal position. These may be over-specified aCC, pCC, CQ, and/or U neurons. The RP2 neurons are generally missing, while the expression of eve in the EL neurons is often reduced. In vnd^hs.PM mutant embryos, the pattern of Fas2-expressing neurons is very disorganised and discontinuous. In addition, the number of Fas2-expressing neurons decreases with age. Fas3-expressing neurons in vnd^hs.PM embryos exhibit pathfinding defects and show a reduction in the number of commissural neurons. Fas3-expressing commissural fascicles are generally not detected in vnd^hs.PM embryos. The number of Fas3 expressing fascicles is reduced in vnd^hs.PM embryos compared to wild-type. Often, two Fas3-expressing fascicles are detected in each hemisegment of vnd^hs.PM embryos. These axons project posterolaterally instead of across the ventral midline as seen in wild-type.

The aCC/pCC and U/CQ neurons are duplicated in embryos expressing vnd^hs.PM.