| 释义 |
platelet factor (PF) 4 plate·let fac·tor (PF) 4 (plāt'lĕt fak'tŏr) A cationic polypeptide synthesized by megakaryocytes and contained in platelet alpha granules; these granules, released when platelets are activated, neutralize the anticoagulant activity of heparin. |