• α-Granules are platelet organelles that are round to oval. They are more numerous and less electron-dense than dense bodies.
• α-Granules contain platelet derived growth factor (PDGF), β-thromboglobulin, platelet factor 4 (PF4), von Willebrand factor (vWF), fibrinogen, factor V, and other proteins.
• Dense bodies contain adenosine triphosphate (ATP), adenosine diphosphate (ADP), serotonin, pyrophosphate, magnesium, and calcium.
• Abnormal or deficient α-granules can lead to platelet dysfunction, such as in gray platelet syndrome.
• In gray platelet syndrome, α-granules are normally formed, but their contents leak from the organelle. Therefore, the α-granules are empty and the platelet does not have its usual granular appearance.
