They are a kind of extracellular vesicle with sizes between 30nm and 150nm. They partially overlap in size with Microvesicles, but their biogenesis is different. Exosomes are associated with endocytic pathway and with endosomal multivesicular bodies' formation[@pedrioli2021Extracellular Vesicles as Promising Carriers in Drug Delivery: Considerations from a Cell Biologist’s Perspective].
There are two known pathways for their biogenesis:
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