= Multivesicular body
A <multivesicular body> is an <endosome> containing multiple small <vesicles> within its lumen. These internal <vesicles> form when regions of the boundary <cell membrane> bud inward and undergo separation. This reverses the familiar direction of a transport <vesicle> budding outward into the <cytosol>.
<Membrane topology> explains a useful consequence. A cytosol-facing portion of a <membrane protein> becomes enclosed inside an internal <vesicle>; subsequent delivery to a <lysosome> can expose the whole cargo to degradation. Sorting onto an internal <vesicle> can therefore remove a signalling <receptor> from the cytosolic machinery that it previously contacted.
A reconstitution experiment added purified <ESCRT-III> components to large artificial <vesicles> and observed formation and detachment of inward buds. This demonstrated a direct membrane-separation activity in a simplified system, rather than merely finding the <proteins> near cellular <multivesicular bodies>.<Membrane scission by the ESCRT-III complex by Thomas Wollert and others>[2009, abstract and giant-vesicle reconstitution]{ref}
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