Electron micrographs of vesicles shed from HuT 78 cells. Arrowheads point to gold particles in association with FasL on plasma membrane-derived vesicles (A). No labeling is observed if vesicles are treated with immunogold particle-conjugated antibody alone (B). Micrograph (A) is 102,000× magnification and micrograph (B) is at 63,000× magnification.