Ultrastructural analysis of PSLPs isolated by density gradient. (A) PSLPs from apheresis PLTs stored for 7 days float in a sucrose density gradient in 3 distinct populations. TEM images of PSLP population collected at (B) d = 1.14 to 1.17 g/mL band composed of DPLT and dense PEVs, (C) d = 1.09 to 1.13 g/mL band composed of large/dense PEVs, and (D) d = 1.02 to 1.06 g/mL composed of ghosts PEVs: membranous vesicles that float to the top of the density gradient. Apheresis PLTs were centrifuged at 1000 g for 30 minutes; the supernatant containing the PSLPs was fixed with 1% paraformaldehyde, pelleted (30 000 g for 20 minutes), and subjected to a sucrose density gradient for 14 hours.