Figure 8.

Dual AAV labeling from cervical and lumbar spinal cord shows distinct patterns of innervation. Adult mice received bilateral injections of AAV2-Retro-EGFP to cervical spinal cord, and AAV2-Retro-tdTomato to lumbar spinal cord. Brains were cleared and imaged 4 weeks later. A–C, Both CST and rubrospinal cell bodies segregated into distinct lumbar versus cervically-projecting populations. D, E, Longer-exposure images of the brainstem reveal distinct populations of lumbar-projecting neurons, including a prominent cluster located in the dorsal pons. a, CST, lumbar projecting; (b) CST, cervical projecting; (c) CST, rostral forelimb area; (d) CST, secondary sensory; (e) red nucleus, lumbar projecting; (e′) red nucleus, cervical projecting; (f) mixed dorsal pontine nuclei; (g) hypothalamic-spinal nuclei; (h) vestibular nuclei; (i) reticular nuclei; (j) cerebellospinal nuclei; and (k) pyramids of corticospinal tract. Error bars: A–C, 2 mm; D, E, 1 mm. A video of cleared tissue is available in Movie 8.