Fig. 2

Exosome (Exo) biogenesis pathway (A). Exos are generated and released using the endosomal system. In the recipient cells, internalized Exos are sequestrated inside the early endosomes followed by maturation into the mature endosomes. Inside the mature endosomes, numerous intraluminal vesicles (ILVs) are generated via the invagination of the endosomal membrane. In this step, several signaling molecules are sequestered into the ILV lumen. After that, late endosomes can mature into MVBs. In the following steps, MVBs can fuse with lysosomes for content degradation or make close connections with cell membranes for the release of ILVs into the extracellular matrix where they hereafter are known as Exos. Ultrastructural images of B lymphocyte with expelled Exos at the plasma membrane. MVBs can be directed toward lysosomal degradation or release their content into the extracellular matrix. Released ILVs (black arrows) are named Exos out of the parent cells. Reprinted adapted from [35]. (Copyright 2016, BMC Biology)