Double immunolabeling for the dense granule marker granulophysin and the -granule marker von Willebrand factor.

Arrowheads indicate granulophysin (10-nm gold particles), and arrows indicate α-granule marker von Willebrand factor (5-nm gold particles). Both proteins can be found within the same MVB, but they are segregated from each other in distinct microvesicles. Granulophysin is also preferentially associated with the limiting membrane of MVBs. Von Willebrand factor is located in α-granules (A) as well as in MVB microvesicles (original magnification ×67 300).