Figure 2.

Schematic representation of the nervous tissue and exosome traffic. Some of the cells presented in Figure 1 are here seen in the central nervous tissue along with a blood vessel. Also present are epithelial cells lining the inside of the blood vessel, the blood–brain barrier (BBB) separating the lumen of the vessel from the nervous tissue, and exosomes secreted by the four types of nervous cells shown. Exosomes follow different routes, as indicated by double parallel arrows, from one cell to another or through the BBB they gain the general circulation and reach distant targets. Conversely, exosomes can traverse the BBB from inside the vessel into the nervous tissue and reach any of the nervous cell types in it.