Fig. 2
From: Non-bone-derived exosomes: a new perspective on regulators of bone homeostasis
Biogenesis and secretion of exosomes. (I) Endocytosis occurs on the surface of the cell membrane and buds inwards to form early endosomes. (II) Early endosomes mature into late endosomes. (III) Through ESCRT-dependent or ESCRT-independent pathways, endosomes achieve cargo sorting and ILV biogenesis and finally form MVBs. (IV) Most MVBs are degraded in the cell after fusion with lysosomes, and some fuse with autophagosomes to form amphisomes. (V) Under the regulation of Rab GTPase, the SNARE complex, the cytoskeleton, molecular motors and other substances, a small proportion of MVBs fuse with the plasma membrane and release their ILVs to the outside of the cell in the form of exosomes