Development of endothelial nitric oxide synthase in endothelial cells in the human cerebrum

We demonstrate the distribution and development of endothelial nitric oxide synthase (eNOS) immunoreactivity in vessels of the human brain. eNOS-positive endothelial cells were recognized in small vessels in the parenchyma of the cerebrum, as well as in the large arteries and veins in the leptomeninges. By 10-13 weeks of gestation, eNOS-positive endothelial cells had already appeared in the vessels of the leptomeninges and deep white matter. Immunoreactivity for eNOS was noted in most vessels at 14-17 weeks in the intermediate white matter, at 18-21 weeks in the cortex, and at 23-26 weeks in the subcortical white matter. Such differences in regional development may be responsible in part for the topographical predilection for hemorrhagic or hypoxic-ischemic lesions in the developing brain.