Fig. 2.

Hypocretin axons with a variety of shapes in rat cord. A, Thin parallel axons entering the gray matter from the dorsolateral white matter. B, Long axons descend from lamina 3/4 down to lamina 7 with boutons at regular intervals in each lamina the axon traverses. C, Axons may traverse the intermediolateral column with frequent boutons.D, Some axons are thick with large numbers of tightly packed boutons investing a small region of lamina 5. E, Lateral to the central canal, axons have frequent branches.F, In the ventral horn, thin axons maintain only a few boutons. Scale bar, 20 μm.