Overview Article: Biostructure of Blood Platelets

Abstract

Advances in biochemistry, physiology, immunology, and cytochemistry, combined with a variety of new approaches for the evaluation of fine structure, have yielded new insights into the structural physiology and pathology of blood platelets. Subpopulations of platelet granules have been clearly defined; they include the catalase containing organelles referred to as peroxi-somes; lysosomes enclosing hydrolytic enzymes; and the α-granules in which platelet factor 4, mitogenic factor, β thromboglobulin, thrombin sensitive protein, fibrinogen, and coagulation factor V are localized. Features of platelet membrane systems have been particularly well-delineated, and recent evidence suggests that membrane complexes serve as the sarcoplasmic reticulum of platelets and the site of prostaglandin synthesis. Improved understanding of platelet biostructure resulting from these observations has made it possible to develop specific relationships between defects in structure and pathological behavior of the cells in vitro and in vivo.

Key Words:

• blood platelets
• α-actinin
• open canalicular system
• dense tubular system
• ultrastructure
• gray platelet syndrome.