White blood cells. Light micrograph of a blood smear showing white blood cells (leucocytes). Making up most of the frame (grey) are the oxygen- transporting red blood cells (erythrocytes). Stained clearly are the infection-fighting white blood cells. At centre (blue) are plasma cells, activated lymphocytes that produce antibodies. Ordinary lymphocytes can be seen at bottom left and upper centre (purple rounded). Beneath the two plasma cells at right is a monocyte (purple). Right of the monocyte is a neutrophil (multilobed nucleus) and a eosinophil (bilobed nucleus). Platelets involved in blood clotting are also present (small blue dots). Magnification unknown.