Ultrastructural comparison of human platelets separated from blood by various means

Ultrastructural features of human platelets separated from blood by a number of different procedures were compared. Platelet isolation procedures included differential centrifugation, gel filtration and albumin density gradient centrifugation. Platelets separated from blood by the differential centrifugation procedure of Mustard showed the least ultrastructural change compared to platelets in plasma. Isolation of platelets from blood by gel filtration produced minor ultrastructural changes including irregularity of cytoplasmic outline, formation of a few short pseudopods and slight dilatation of the surface-connected canalicular system. Platelets separated by albumin density gradient centrifugation showed the most marked alterations of ultrastructure. Ultrastructural features of platelets isolated by the various procedures are compared to functional changes previously reported.