BONE MARROW INSUFFICIENCY

The bone marrow is considered today to be an integral organ with many important functions. According to Middleton and Meyer,¹ under normal conditions it is the sole source of the red blood cells, the polymorphonuclear leukocytes and the thrombocytes in adult life. The functioning red bone marrow occupies the entire shafts of the long bones at birth. By the sixteenth year of life, active bone marrow is found in the ends of the long bones, in the flat bones, and in small, spongy bones. The histogenesis of the mature blood cells arising in the marrow is not completely understood. However, it is generally accepted that the root cell or hemoblast is responsible for the development of the polymorphonuclears, the erythrocytes and the platelets. The megakaryocyte of the marrow is believed to be the only source of the thrombocyte; but under disease conditions these large cells may appear in other