EM findings on the source of reactive microglia on the mammalian brain.
In traumatic brain lesions microglia cells are often plastered on the outer surface of capillaries. Basement membranes delimit these juxtacepillary cells from pericytes and endothelial cells. In altered nervous tissue many stages in the activation of pericytes may be seen at the same time. It is clearly demonstrable that these pericytes attack the basement membrane vigorously from inside. After penetration of the basement membrane these cells propel themselves between the perivascular feet processes of astrocytes and squeeze between the intracellular gaps, becoming surrounded by the cell processes of the neruopil. The observations suggest that in reactive stages in microglia cells may, at least in part, originate from the perivascular mesenchymal tissue.
D000818:Animals; D001485:Basement Membrane / Q000648:ultrastructure; D001930:Brain Injuries / Q000473:pathology; D002196:Capillaries / Q000648:ultrastructure; D002465:Cell Movement; D002540:Cerebral Cortex / Q000648:ultrastructure; D006224:Cricetinae; D004727:Endothelium / Q000648:ultrastructure; D005110:Extracellular Space / Q000648:ultrastructure; D012157:Mononuclear Phagocyte System / Q000648:ultrastructure*; D009457:Neuroglia / Q000648:ultrastructure*