Ultrastructural localization of adenosine diphosphatase activity in cultured aortic endothelial cells.

Electron microscopy cytochemical studies demonstrate that the plasma membrane of cultured aortic endothelial cells contain significant amounts of adenosine diphosphatase. The activity is due to an ectoenzyme on the upper surface of the cell. Intracellular activity was noted in multilamellar bodies.