Fig. S3

Complete and selective ablation of motor neurons in mouse. (A-C) Lateral wholemount view of E10.5 mouse control embryo (upper thoracic to cranial levels): normal appearance of peripheral axon projections (A,C) (grey: anti-Tuj-1 immunofluorescence). Anti-Isl1/2 immunofluorescence (red) visualizes nuclei of DRG neurons (in ganglia lining the neural tube) and motor neurons (MNs) (arrowheads: motor column within ventral neural tube) (A,B). Abbreviations: SCG (sympathetic chain ganglion neurons), BP (brachial plexus). (DF) Lateral wholemount view of E10.5 mouse embryo upon MN ablation (Olig2Cre;Rosa26lxstopDTA): Complete absence of MNs and pure motor nerves (XII, asterisk) (D,E), but normal appearance of DRGs and sympathetic chain ganglia (scg) (D,F). (G,H) Transversal section of E10.5 control spinal cord (sc): extension of MEs from MNs (magenta: anti-vAChT immunofluorescence) (G) and presence of DRG neurons and MNs (red: anti- Isl1/2 immunofluorescence) (H). (I,J) Transversal section of E10.5 Olig2Cre;Rosa26lxstopDTA spinal cord: complete absence of MEs (I, J), but not DRG neurons (J). (K) Dorsal wholemount view of SAs (yellow: Brn3atlz) at sciatic plexus (SP) in E12.5 mouse. Abbreviations: CP (crural plexus), DPN (deep peroneal nerve), PN (peroneal nerve), TN (tibial nerve). (L) Near-total failure of SAs (arrowheads) to innervate limb beyond plexus in the absence of MEs in Olig2Cre;Rosa26lxstopDTA embryo (asterisk). Scale bars: 200 µm in C,F,G,H,I,J,K,L.