Mature erythrocytes are mature red blood cells after further development of reticulocytes. The vast majority of red blood cells in human peripheral blood are mature red blood cells, and the main function of mature red blood cells is to transport oxygen and carbon dioxide. Because there is hemoglobin inside the red blood cells, hemoglobin can combine with oxygen to form oxyhemoglobin, and then transported to the tissues and organs, oxygen and oxygen and hemoglobin are separated, and oxygen will be available for the tissues and organs to use. At the same time the carbon dioxide produced by the tissue organs will in turn combine with hemoglobin to form carboxyhemoglobin, which is then transported to the lungs and excreted through the lungs. So the main role of mature red blood cells is to transport oxygen and carbon dioxide. When the number of red blood cells decreases, that is, when there is anemia, the function of transporting oxygen decreases and the patient becomes anemic.