When lblScer\UAS.cJa is driven by Scer\GAL4l(3)31-1-31-1 defects in CNS morphology is seen. There is a thinning or absence of the posterior commissures in some neuromeres and a fusion of the commissures in others. The EL neurons deriving from NB 3-3 are also defective. Supernumerary subperineural and exit glial cells are also seen. The distance between the ISN and SN nerve clusters is decreased.