High voltage electron microscopic studies of endothelial cell tubular structures in the mouse blood-brain barrier following brain trauma.

High-voltage electron microscopy was applied to the study of endothelial cell (EC) transport of macromolecules in a murine model of blood-brain barrier injury to study the role of the EC canalicular system following brain insult. Semithick sections from mouse brains subjected to acute (2-3 h) mechanical trauma demonstrated permeation of intravenously injected horseradish peroxidase via tubular structures either (a) in the absence of lysosome-associated structures in close proximity, or (b) in association with lysosomes, dense bodies or multivesicular bodies. Our data suggest a dual-purposed system of tubules, one portion that supplies the metabolic requirements of the cell and another portion, suggested to be more limited, that opens up as a result of brain injury.