GDNF is dispensable for SC migration along embryonic sympathetic axons. A/B: bright field images taken during time-lapse imaging (scale bar 100 μm). A: control SCG explant treated with NGF. A multitude of axons are visible and SCs along the axons (arrowheads). B: SCG explant of GDNF KO. Also many axons are visible, surprisingly also covered by SCs (arrowheads). C-F: Immunohistochemical stainings (scale bar 200 μm), Thyrosine hydroxylase (TH, red) and s100 (green) immunostainings with DAPI nuclear counterstaining. In both control (C/E) as well as in the GDNF KO explants (D/F) many sympathetic axons labeled by TH can be seen, covered with s100-ir positive labeled SCs. C/D: E18.5, E/F: E15.5.