Immuno-electron microscopic localization of endothelial nitric oxide synthase in human placental terminal villous trophoblasts-normal and pre-eclamptic pregnancy.

We demonstrated the subcellular localization of endothelial nitric oxide synthase (eNOS) in human placental terminal villous trophoblasts at near term period, and compared the distribution pattern with that in pre-eclamptic trophoblasts, using immunogold electron microscopy. Immunolabelling for eNOS was visible markedly in the syncytial microvilli and syncytial cytoplasm. Semiquantitative analysis showed that the concentration and the distribution pattern of gold particles for eNOS did not significantly differ between normal and pre-eclamptic placental trophoblasts. These results indicated that syncytiotrophoblastic microvilli and cytoplasm were the subcellular localization sites of syncytium-derived eNOS in terminal villi, and that there were no significant differences in this eNOS subcellular distribution pattern between normal and pre-eclamptic syncytiotrophoblasts in regard to immunohistochemically detectable eNOS. Copyright 2001 Harcourt Publishers Ltd.