Abstract: Objective To explore the rule of the expressions of neuronal nitric oxide synthase(nNOS) and vascular endothelial growth factor(VEGF) in the early developing human fetus. Methods At the second to fourth month of gestation, the expressions of nNOS and VEGF were observed in 14 cases of human fetal small intestine villi by using the SABC and PV of the immunohistochemical methods. Results In the second month of gestation, the expression of nNOS was negative and VEGF was positive at the epithelial cell layer in the small intestinal villi of human fetus. At the third to fourth month of gestation, the expressions of nNOS and VEGF proteins were positive in some cells of the small intestinal villi of human fetus. Conclusion nNOS and VEGF proteins are closely related to the growth and development of the cells and tissues in the early developing small intestinal villi of human fetus.

Key words: Small intestine, Neuronal nitric oxide synthase, Vascular endothelial growth factor, Immunohistochemistry, Human fetus