The morphology of the dorsal root ganglion and ventral roots (cross section) with HE staining at 20 weeks after C7 and C8 ventral root avulsion. In normal group, the boundary of the DRG and ventral root were clearly recognized. The structure of axons in the ventral roots were well organized (A-a). In the Av + PBS subgroup, only the boundary of the DRG could be found, and the ventral roots were totally absent (B-b). In the Av + Li subgroup, the intact structure of the DRG was demonstrated with the residual part of the avulsed ventral root (C-c). In the Re + PBS subgroup, the regenerative ventral root was clearly recognized with 3 rootlets adjacent to the DRG wrapped in an intact epineurium. A large amount of Schwann cells were distributed among the axons (D-d). In the Re + Li subgroup, the ventral roots were closely attached to the DRG with an intact epineurium, and some axons in the regenerative ventral roots were wrapped with a thinner myelin sheath (E-e). Scale bar = 200 μm.