Editing Platelet (section)

=====Granule secretion=====
[[File:Platelet structure.png|right|thumb|Diagram of the structure of a platelet showing the granules]]
Platelets contain [[dense granules]], lambda granules, and [[alpha granule]]s. Activated platelets secrete the contents of these granules through their canalicular systems to the exterior. Bound and activated platelets degranulate to release platelet [[chemotactic]] agents to attract more platelets to the site of endothelial injury. Granule characteristics:
* [[Platelet alpha-granule|α granules (alpha granules)]] — containing [[P-selectin]], [[platelet factor 4]], [[TGF beta 1|transforming growth factor-β1]], [[platelet-derived growth factor]], [[fibronectin]], [[B-thromboglobulin]], [[von Willebrand factor|vWF]], [[fibrinogen]], and [[coagulation factor]]s [[factor V|V]] and [[factor XIII|XIII]]
* [[dense granule|δ granules (delta or dense granules)]] — containing [[adenosine diphosphate|ADP]] or [[adenosine triphosphate|ATP]], [[calcium]], and [[serotonin]]
* γ granules (gamma granules) — similar to [[lysosome]]s and contain several hydrolytic enzymes
* λ granules (lambda granules) — contents involved in resorption during later stages of vessel repair