Figure 1. Orexinergic innervation of the developing (P3) spinal cord. A, Longitudinal section of spinal cord (30 μm) showing numerous orexinergic fibers projecting along the lateral funiculus throughout the lumbar spinal cord. Scale bar, 500 µm. Corner schematic shows the location of the longitudinal section (LF, lateral funiculus; PG, preganglionic motor neurons); 60× confocal images of select regions (scale bar, 50 µm): i, sparse orexinergic fibers around MNs in lumbar region; ii, dorsal fibers in the L1-L2 region; iii, rare fiber passing by L1-L2 MNs; iv, orexinergic fibers exiting the LF around the preganglionic MNs; v, orexinergic fibers in the LF, varicosities are evident. B, Positive control showing OXergic neurons in lateral hypothalamus. C, Transverse sections of L1-L2 spinal cord with rhodamine-labeled dCINs and rhodamine-labeled ventral MNs (scale bar, 250 µm); 60× confocal images of select regions (scale bar, 50 µm): i, orexinergic fibers apposing dCINs; ii, sparse fibers in MN pool; iii, orexinergic fibers exiting the LF around the preganglionic MNs; iv, dorsal fibers are prevalent.