Platelets are produced by bone marrow cells called megakaryocytes, which undergo a process of division as they develop into giant cells, resulting in the release of more than 1,000 platelets per megakaryocyte. Platelets are produced in the bone marrow and the main hormone that controls the development of megakaryocytes is thrombopoietin (often abbreviated as TPO). Platelets are not actually real cells, but are a formative component of megakaryocyte maturation. Platelets contain proteins on their surface that allow them to adhere to breaks in the blood vessel wall and to each other. Platelets also contain granules that secrete other proteins that are needed to form a strong plug to seal a ruptured blood vessel. When the endothelial layer is ruptured by an injury or cut, the tough fibers surrounding the blood vessel are exposed to the flowing blood. Platelets are the first to respond to the injury and are involved in the hemostatic process, and high or low platelets can affect the body’s function. Increased or decreased platelets can be very dangerous to the body, if the test is abnormal, it is recommended to go to the hospital in time.