Fig. 4.

Transverse sections through medullary reticular formations and red nucleus showing retrograde labeling of supraspinal neurons extending axons into the grafted nerve. Two months after PN grafting, the retrograde tracer CTβ was microinjected in the reinnervated muscle. (A) A section from the medullary reticular formation showing the staining of neurons in the nucleus gigantocellularis. Higher-magnification micrograph (Inset) is shown in B. A section from midbrain (C) showing a number of neurons labeled in the red nucleus controlateral to the grafted side and fewer cells stained at the ipsilateral side. Higher-magnification micrograph of controlateral red nucleus (Inset) is shown in D. (Bar, 650 μmin A and C; 200 μmin B and D.)