Figure 1: Glial populations around the midline. The locations of the midline glial populations on a coronal section of the E15.0 mouse brain are shown. These populations are mainly composed of four structures: the glial wedge (GW), the indusium griseum (IG), the midline zipper (MZ), and the glial sling (GS). These populations guide the growth of the callosal axons and help them cross the midline in the CC. LV: lateral ventricle.