CYTOARCHITECTURE OF PERIENDOTHELIAL CELLS IN HUMAN CEREBRAL VENOUS VESSELS AS COMPARED WITH THE SCALP VEIN - A SCANNING ELECTRON-MICROSCOPIC STUDY

Three-dimensional cytoarchitectures of the periendothelial cells of hu man cerebral venous vessels as well as a scalp vein were studied by sc anning electron microscopy after removal of extra-cellular connective tissue matrices with a KOH-collagenase digestion method. Postcapillary venules appeared covered with pericytes, while collecting venules had stellate periendothelial cells which formed a basket-like network aro und the vessel wall. As the size of the venous vessels increased, the stellate periendothelial cells became flat in shape and dense in arran gement. Although they had some characteristics similar to the smooth m uscle cells in surface structure, no spindle-shaped smooth muscle cell s were recognizable even in the superficial cerebral veins. On the oth er hand, the scalp vein was densely covered with spindle-shaped smooth muscle cells running circularly. These findings suggest that the cere bral venous vessels cannot constrict strongly as compared with the sca lp vein, but probably regulate blood volume by mildly changing the cal iber of the vessels.