Platelets make up ____________ of formed elements with a concentration between 150,000 and 400,000 per cubic millimeter. The production of platelets is called ____________ . From the myeloid stem cell, a committed cell called a ____________ is produced. It matures under the influence of the hormone ____________ to form a ____________ . These cells have a large size and a dense, multilobed nucleus. Each of these large cells produce long extensions from themselves called ____________ . While still attached, these extensions pass through the blood vessel wall in the red bone marrow. The force from the blood flow “slices” these extensions into ____________ .