Microglia. Coloured scanning electron micrograph (SEM) of protective cells of the human immune system known as a microglia. Microglia process foreign antigens then act like an alarm signal, alerting other immune cells of the body to the infection. The long projections seen on the cell's surface are "feet" to help it move. Dendritic cells found in the central nervous system are known as microglia, in the upper layer of the skin (the epidermis) they are known as histiocytes or Langerhans cells. and in the liver as Kupffer cells. Magnification:x1300 when printed at 10cm high.