Figure 6. Zic2 Spinal Neurons Synapse with Spinal Motor Neurons.
(A) Intersectional strategy to exclusively visualize Zic2creER spinal neurons. CAG promoter; FRT and loxP, recognition sites for Flp and Cre recombinases, respectively.
(B) Transverse section of a P15 lumbar SC Zic2-creER;Cdx2FlpO::Ai65D immunolabeled with mCherry (red) and ChAT antibodies (green). Note tdTomato+ axons surrounding motor neurons (B’).
(C) Experimental strategy to visualize Zic2creER pre-synaptic terminals (green) and retrogradely labeled spinal motor neurons with CTB injections in the quadriceps muscle (red).
(D) Transverse section of Zic2creER; Taulox-STOP-lox-SynGFP lumbar SC retrogradely traced with CTB (red) and immunolabeled with GFP (green) and vGluT2 antibodies (blue). SynGFP marks Zic2+ terminals co-localizing with vGluT2 on CTB labeled motor neurons (D’ and D”).
Scale bars, 100 mm (B and D), 10 mm (B’), 5 mm (D’), and 2 mm (D”).