Fig. 1

Classification and biogenesis of extracellular vesicles. Cells can assimilate extracellular substances by plasma membrane invagination and endocytosis. The late sorting endosomes (LSEs) are transformed from vesicles fused with the early sorting endosomes (ESEs). Intraluminal vesicles (ILVs) are caused by a second invagination of the LSEs. Multivesicular bodies (MVBs), further transformed from LSEs, can fuse with lysosomes or autophagosomes for degradation, or with the plasma membrane to release ILVs, which are termed small extracellular vesicles. Microvesicles are produced from the outward budding and fission of the plasma membrane. Apoptotic bodies are large vesicles formed by apoptotic cells