Caption

Lymphocytes. Coloured scanning electron micrograph (SEM) of two lymphocytes, a common type of white blood cell. The cells' cytoplasm is dividing (cytokinesis) following mitotic cell division. The long microvilli which project from the surface of these rounded cells are thought to assist in cell motility. Lymphocytes are involved in the immune response, acting to protect the body against infection. There are two main types of human lymphocytes: T-cells and B-cells. T-cells (thymus- derived) track down and destroy foreign bodies, while B-cells (bone marrow-derived) identify foreign micro-organisms and make antibodies. Magnification: x3000 at 6x9cm size.