The ultrastructural change of sciatic nerve and immunohistochemical changes of NGF, PCNA were studied at the transplanted segment of intravascular cultured neural stem cell in the rat sciatic nerve by 5 months after the sciatic nerve transection. The transplanted intravascular neural stem cells were differentiated into Schwann reals at the 20th day and these cells began to regenerate by the proliferation and hypertrophy. There were many remyelinating Schwann cells in the transplanted nerve in term of stimulation. According to NGF finding, we suggest preexisting Schwann cells may induce the differentiation of neural stem cells into regenerating Schwann cells. Electron microscopic changes were the remyelinating appearance, the increase of intraaxonal microtubules and enlarged mitochondria and contacting tell processes each other.