Final answer:
More than half of the body's blood platelets are made by megakaryocytes in the bone marrow through a process called hematopoiesis.
Step-by-step explanation:
More than half of the body's blood platelets are made by megakaryocytes in the bone marrow. Megakaryocytes are large cells that release thousands of cytoplasmic fragments, each enclosed by a bit of plasma membrane, which are known as platelets. This process, called hematopoiesis, occurs in the red marrow of bones and is essential for the continuous production of blood cells and platelets.