Final answer:
The hormone responsible for stimulating the formation of platelets is thrombopoietin, a glycoprotein hormone from the liver and kidneys that causes megakaryocytes to develop into platelets.
Step-by-step explanation:
The substance that stimulates the formation of platelets is thrombopoietin. Thrombopoietin is a glycoprotein hormone produced primarily by the liver and kidneys. It plays a crucial role in hematopoiesis by triggering the development of megakaryocytes into thrombocytes, more commonly known as platelets. Platelets are critical for the clotting process in the body, helping to prevent excessive bleeding.
It should not be confused with erythropoietin, which is a hormone produced by the kidney that stimulates red blood cell production. Unlike colony-stimulating factors and interleukins, which stimulate the proliferation and differentiation of other formed elements in the blood, thrombopoietin specifically targets the production of platelets.