Immunostaining of axons and midline glial structures at E17.5 in Slc12a6^Δ18/Δ18 KO and WT mice. A, C, E, The integrity of growing axons was assessed using immunohistochemistry for GAP-43 in brain coronal sections from both KO lines and WT mice. B, D, F, The three prominent midline glial populations were found to be present when visualized using immunohistochemistry for GFAP. These glial populations included the indusium griseum glia (IGG), the glial wedge (GW), and the midline zipper glia (MZ). Scale bar, 200 μm. n = 3.