Abstract: Objective To explore the rule of distribution and expression significance of neuronal nitric oxide synthase（nNOS）, vascular endothelial growth factor （VEGF） and Bcell lymphoma/leukemia2（Bcl-2）proteins in the developing spinal cord anterior horn of human embryos. Methods In the fourth month of gestation, the expression productions of nNOS, VEGF and Bcl-2 proteins were investigated in the anterior horn of human embryonic spinal cord using the immunohistochemical methods. Results The intensities of the immunohistochemical signals of both nNOS and Bcl-2 proteins were progressively enhanced from the second to the fourth month of gestation. There was negative immunohistochemical signals of VEGF in the anterior horn of human embryonic spinal cord in the second month of gestation. At the third to fourth month of gestation, the expression of VEGF protein was from weak to strong in the anterior horn of human embryonic spinal cord. Conclusion nNOS, VEGF and Bcl-2 proteins a

Key words: Spinal cord, Neuronal nitric oxide synthase, B-cell lymphoma/leukemia-2, Vascular endothelial growth factor, Immunohistochemistry, Human embryo