Microglial cell. Scanning electron micrograph of a human microglial cell activated due to stimulation by an antigen (foreign substance). The fine projections produced on such activation are known as filopodia. Microglia are macrophages found in the central nervous system, having migrated from circulating blood to neural tissues. In addition to a scavenging role, microglia are capable of processing antigens during the initial phase of immune response. Processed antigens are presented on the cell's surface so they might be recognized and ultimately eliminated by specific lymphocytes. Microglia are implicated in multiple sclerosis. Magnification: x1600 at 4.5x6.5inch size.