Figure 2.

Overview of Extracellular Vesicle (EV) Biogenesis, Secretion, and Uptake.

(A) Transmission electron microscopy images of EV subtypes (exomeres, exosomes, microvesicles, and apoptotic bodies) and their approximate sizes [1,6,214,215]. (B) EV biogenesis pathways. Exosomes are formed through inward budding of the cell membrane and the formation of multivesicular endosomes, which capture exosomes then fuse with the cell membrane and release exosomes through exocytosis [1]. Microvesicles are formed through outward budding of the cell membrane and apoptotic bodies are formed during cell apoptosis and death [1,6]. (C) EV subtype cargo. Each subtype of EVs contains a different cargo. Exosomes and microvesicles contain membrane proteins and tetraspanins, while apoptotic bodies also carry fragments of cell organelles from apoptosis [12,13]. (D) EV uptake occurs through the internalization of the EV into the cell by either docking or fusion of the membranes. Endosomes can also be created, and then release their EV content into the cell [4,5]. Reprinted, with permission, from referenced sources.