Histomorphologic changes of the spinal cord after the surgeries. A: A transverse plane image of the C6 spinal segment at 12 h after extra-vertebral nerve root avulsion. The black arrow indicates the intraspinal bleeding along the motor neuron axons in the ventral spinal cord. The asterisk indicates the lesioned side. B: A transverse section of the ventral horn of the lesioned side at 12 h after extra-vertebral avulsion with hematoxylin-eosin staining. The black arrows indicate intraspinal bleeding along the axons of the motor neurons. (Bar: 200 μm.) C: A transverse section at 28 days after intradural ventral root avulsion (group A). Spinal cord deformity was found on the lesioned side (*). (Bar: 1 mm.) D: A transverse section at 28 days after extra-vertebral nerve root avulsion (group C). The spinal cord was almost intact on the lesioned side (*) (Bar: 1 mm.).