The Treaty of Kanagawa was an 1854 agreement between the United States of America and the government of Japan. The treaty, which was essentially imposed on the Japanese by threat of force, opened two Japanese ports for trade with American ships. The treaty was the first modern treaty Japan had with a western nation.
Platelets have no cell nucleus: they are fragments of cytoplasm that are derived from the megakaryocytes of the bone marrow, and then enter the circulation. These unactivated platelets are biconvex discoid (lens-shaped) structures, 2â3 Âµm in greatest diameter.
Donating Platelets. Platelets are blood cells that help control bleeding. When a blood vessel is damaged, platelets collect at the site of injury and temporarily repair the tear. You can think of platelets like bricks that gather together at a blood vessel tear. After the platelets are activated, plasma then helps the blood clot by holding the platelets together. You can think of plasma as the cement that stabilizes the platelet bricks. Once a clot is formed, the wound can heal.