He is a specialist in Hematology. Hematology is the medical specialty that studies the blood, the hematopoietic organs (the bone marrow, the lymph nodes and the spleen being the main ones) and their diseases. all the phenomena which contribute to the production and replacement of blood cells, namely: red blood cells or erythrocytes, which transport oxygen to the various organs and tissues of the body; white blood cells or leucocytes (monocytes, lymphocytes, eosinophils, basophils and neutrophils), which defend the body against infections or the presence of foreign bodies. These are cells of the immune system; and platelets, which are responsible for clotting the blood and making it possible to stop bleeding. These cells are synthesized from the same so-called hematopoietic stem cells in the bone marrow.