LM of a smear of human blood consisting of red cells (erythrocytes) and two white blood cells (leucocytes) in the center. The function of the erythrocytes is the distribution & transportation of oxygen and carbon dioxide to and from the cells of the body. Surrounded by a thin elastic membrane, the whole of the interior is filled with the red pigment haemoglobin, which has a good oxygen carrying capacity. Erythrocytes have a biconcave disc shape & are flexible so that they can accommodate themselves to the smallest of capillaries. The function of the leucocytes is that of defense against disease. Magnification x210 at 35mm size, x420 at 6x7cm size.