Fig. 1.

Biogenesis and release of extracellular vesicles.

Extracellular vesicles can be broadly classified into 3 main classes: (a) Microvesicles/microparticles/ectosomes that are produced by outward budding and fission of the plasma membrane; (b) Exosomes that are formed within the endosomal network and released upon fusion of multi-vesicular bodies with the plasma membrane; and (c) Apoptotic bodies are released as blebs of cells undergoing apoptosis. Lower organisms, such as bacteria and parasites, are also able to secrete EVs. Outer membrane vesicles (OVM) are formed by outward bulging of the outer membrane of gram-negative bacteria. EE=early endosome; MVB=multi-vesicular body; ILV=intraluminal vesicles; N=Nucleus; OM=outer membrane; Pp=periplasm; IM=inner membrane; n=nucleoid; F=flagella.