Lymphocyte white blood cell. Comparison between a scanning election micrograph (SEM left) and transmission electron micrograph (TEM right) of a lymphocyte. Lymphocytes are involved in the immune system's defence mechanisms, lymph system, and antibody production. The TEM image shows the large central nucleus surrounded by the cytoplasm containing mitochondria. The SEM image shows the large number of small microvilli on the surface typical of lymphocytes. Magnification: x10, 000 when printed 10 centimetres high. For a series of comparisons between SEMs and TEMs see images C047/7006 to C047/7034.