FIG. 4.

Representative longitudinal (horizontal) sections through the cervical spinal cord of rats, 16 weeks after high cervical lateral hemisection (C2Hx) injury, 72 (A–C) and 96 (D–F) h after injection of pseudorabies virus (PRV) into the left extensor carpi radialis longus (ECRL) muscle. Sections have been immunolabeled for the presence of PRV. Low resolution images (A–F) demonstrate the distribution of PRV labeling in the cervical spinal cord, and high resolution images (insets, panels D–F) demonstrate ECRL motoneuron and interneuron morphology. Motoneuron labeling was evident in the ipsilateral ventral horn (C and F), as well as bilateral interneuronal labeling in the intermediate gray matter (B and E) and dorsal horns (A and D) at the 96 h post-injection time point. As compared with uninjured controls, first-order PRV labeling at the 72 h time point was reduced, although at 96 h, significant interneuronal labeling was evident, extending throughout the cervical spinal cord in both the dorsal horn and the intermediate gray matter (D–E). Rostrocaudal orientation is from left to right. Scale bars: 1 mm (panels A–F) and 100 μm (inset panels).