Release of exosomes from activated platelets. Thin frozen sections of a platelet aggregate after activation with 1 U/mL of -thrombin in the absence of dRGDW. Immunolabeling with anti-CD63 and protein-A gold (10 nm). (a) Exocytotic profile of multivesicular body containing CD63⁺ exosomes (star). (b) Exosomes detected in the extracellular area between platelet pseudopods (arrowheads). Bars: 100 nm.