The reason why quantitative and qualitative diagnosis based on the cellular components of the blood is so important is that blood cells are easily accessible indicators of disturbances in their organs of origin or degradation—which are much less easily accessible. Thus, disturbances in the erythrocyte, granulocyte, and thrombocyte series allow important conclusions to be drawn about bone marrow function, just as disturbances of the lymphatic cells indicate reactions or disease states of the specialized lymphopoietic organs (basically, the lymph nodes, spleen, and the diffuse lymphatic intestinal organ).