On the Fine Structure and Aggregation Requirements of Gel Filtered Platelets (GFP)

Abstract

Hamster platelets separated from plasma by gel filtration (GFP) have been subjected to further studies: (1) The intraplatelet organelles of the GFP as examined by the electron microscope have an appearance similar to those of platelets in plasma and of platelets washed by centrifugation (CP). (2) The frequency of pseudopods exhibited by the GFP and platelets in PRP was significantly less than in the preparations of CP. However, GFP had more platelets with three or more pseudopods than did platelet left undisturbed in citrated plasma. (3) Electron microscopy of the GFP during ADP‐induced aggregation showed these platelets to behave morphologically as PRP. (4) The Ca ++ and Mg ++ requirements of GFP in ADP‐induced aggregation were similar to those reported earlier by other workers. (5) Addition of fibrinogen to GFP was not required for ADP‐induced aggregation. (6) Albumin stabilized the GFP so that the platelets remained responsive to ADP for at least 3 h after gel filtration.