The bone marrow produces stem cells<span>, the building blocks that the </span>body<span> uses to </span>make<span> the different </span>blood cells for example <span>red </span>cells<span>, white </span>cells<span> and platelets. The erythropoietin sends a message to the stem </span>cells<span> telling more of them to develop into red </span>blood cells<span>, rather than white </span>cells<span> or platelets</span>
