Multiple Slits regulate the development of midline glial populations and the corpus callosum

► Corpus callosum defects are observed in Slit single and compound mutants. ► Slits mediate callosal development by regulating axonal guidance and midline glial development. ► Slit2 is the predominant family member involved. ► Slit2−/− and Robo1−/− mice display phenotypic differences in post midline-crossing axons.