Ultrastructural cytochemical studies of cerebral microvasculature in scrapie infected mice.

Alkaline phosphatase, 5'-nucleotidase nucleoside diphosphatase and thiamine pyrophosphatase activities were studied by cytochemical method applied to electron microscopy of brain microvasculature in normal and scrapie infected mice. In control mice, the major location of all phosphatases studied was the luminal plasma membrane of the endothelial cells. In scrapie infected mice, changes in activity and distribution of the above mentioned phosphatases manifested themselves in the appearance of the reaction product on the abluminal side of the vessel wall. Our data presents evidence that following scrapie infection, these enzymes change their specific localization along the endothelial cell membranes. These enzymatic changes may serve as useful indicators of some alterations in the mammalian blood-brain barrier following infection by scrapie agent in the mouse.