Intercellular communication by extracellular vesicles with emphasis on the roles of cordocytes in the human brain. An ultrastructural study.

We describe in this work the presence of extracellular vesicles (EVs) along different cell types, especially cordocytes, in various clinical conditions of the human brain (atherothrombotic disease, cerebral tumors, hygroma durae matris, intracerebral cysts, Moyamoya disease and parenchymatous hematoma) using transmission electron microscopy (TEM). EVs, illustrated as exosomes and microvesicles, were causally related to cell-to-cell communication, and other vital functions of resident cells around the brain parenchyma, either around the cortical vessels or into the subarachnoid space and the reticular arachnoid. Our direct demonstration by TEM of these information transporters in all locations and situations where the cordocytes play coordinating and regulating roles, producing and delivering a significant number of EVs to their targets, remains to be better documented in future studies.