Highly motile brain macrophages/microglial cells were observed in the cingulum and supraventricular corpus callosum, an area termed by del Rio‐Hortega the “fountain of microglia.” This is the first study that uses time lapse video microscopy in acute cortical brain slices to analyze directly the motile and phagocytic behaviour of these cells. The cells migrated within minutes to the slice surface and actively screened their surrounding with velum‐like processes. Dead/damaged cells on the slice surface were contacted by the processes and phagozytozed within minutes. A method to add red blood cells in a defined density was used to observe the phagocytosis. © 1996 Wiley‐Liss, Inc.