Fig. 6. ß-spectrin^kus interacts with slit. (A) In wild-type stage-16 embryos, three distinct fascicles can be recognized following Fasciclin II staining. The most medial fascicle never crosses the CNS midline (see C for quantification). (B) In hemizygous-mutant ß-spectrin^kus embryos, the inner fascicles appear to cross the midline (arrow). (D) Hemizygous-mutant kus embryo also lacking one copy of slit. The number of ectopic midline crosses increases significantly (arrows). (C) Quantification of the number of midline crosses of Fasciclin II-positive axon bundles. The number of embryos counted, the average number of ectopic crosses per embryo and the standard deviation for each genotype is indicated.