It is a disease of the bone marrow -- the semi-liquid tissue inside bones that produces blood cells. Stem cells in the bone marrow develop into two types of cells, myeloid and lymphoid. Lymphoid cells go on to become white blood cells that fight infections. Myeloid cells develop into three different types of cells: red blood cells, which carry oxygen platelets, which control bleeding by forming clots and white blood cells. In myeloplastic syndrome the myeloid cells stop developing they do not function normally and either die in the bone marrow or soon after they enter the blood. The dysfunctional cells crowd out healthy cells.-It is a disease of the bone marrow -- the semi-liquid tissue inside bones that produces blood cells. Stem cells in the bone marrow develop into two types of cells, myeloid and lymphoid. Lymphoid cells go on to become white blood cells that fight infections. Myeloid cells develop into three different types of cells: red blood cells, which carry oxygen　platelets, which control bleeding by forming clots　and white blood cells. In myeloplastic syndrome the myeloid cells stop developing　they do not function normally and either die in the bone marrow or soon after they enter the blood. The dysfunctional cells crowd out healthy cells.