Table 1.

Classification and characteristics (Thery et al. 2009; van der Pol et al. 2012; Akers et al. 2013; Ciardiello et al. 2016) of extracellular vesicles (EM electron microscopy, ND not determined, TNFRI tumour necrosis factor receptor I)

Characteristic	Exosomes	Microvesicles	Ectosomes	Membrane particles	Exosome-like vesicles	Apoptotic bodies
Size	50-100 nm	20-1000 nm	50-200 nm	50–80 to 600 nm	20-50 nm	50-500 nm and 500-4000 nm
Density in sucrose	1.13–1.19 g/ml	ND	ND	1.04–1.07 g/ml	1.1 g/ml	1.16–1.28 g/ml
EM morphology	Cup shape	Irregular shape and electron-dense	Bilamellar round structures	Round	Irregular shape	Heterogeneous
Sedimentation	100,000 g	10,000–20,000 g	160,000–200,000 g	100,000–200,000 g	175,000 g	1200 g, 10,000 g or 100,000 g
Lipid composition	Enriched in cholesterol, sphingomyelin and ceramide; contain lipid rafts; expose phosphatidylserine	Expose phosphatidylserine	Enriched in cholesterol and diacylglycerol; expose phosphatidylserine	ND	Do not contain lipid rafts	Expose phosphatidylserine
Main protein markers	Tetraspanins (CD63, CD9), Alix and TSg101	Integrins, selectins and CD40 ligand, VCAMP3, ARF6	CR1 and proteolytic enzymes; no CD63	CD133; no CD63	TNFRI	Histones, caspase3, C3b
Intracellular origin	Internal compartments (endosomes)	Plasma membrane	Plasma membrane	Plasma membrane	Internal compartments	Plasma membrane, endoplasmic reticulum