From News Medical Net
Exosomes are vesicles, or cellular components, that exist outside of a cell. They are generally understood as having been released from cells upon fusion with an intermediate endocytic compartment, or a multivesicular body (MVB).
When the MVB fuses with the plasma membrane surrounding the cell, intraluminal vesicles are released into the extracellular matrix and become exosomes. Other types of vesicles found outside of cells include apoptotic bodies and ectosomes. These are distinct types of vesicles from the exosome.
History of exosomes
Extracellular vesicles were first identified~50 years ago, and were assumed to be waste products of the cell. In 1983, studies on the loss of transferrin during maturation of reticulocytes into erythrocytes led to the characterization of the exosome.
For the first time, the observation was made that MVBs can produce intraluminal vesicles (ILVs) that are then released into the extracellular space through fusion with the plasma membrane. ILVs were subsequently named exosomes.