Demonstration of P-selectin and CD63 in cultured megakaryocytes. Labeling as indicated on the figure. P-selectin is present in the Golgi-complex (g), α-granules (α), and MVBs (asterisks). Colocalization with CD63 (arrowheads) is restricted to the MVBs. (B and C) Selected MVBs from megakaryocyte origin. Immunolabeling as indicated on the figure. Bar, 250 nm.