[Role of perivascular phagocyte (FGP) of cerebral small blood vessel in cerebral edema].

Small cerebral blood vessels are provided with slender phagocytic cells which were designated as FGP (fluorescent granular perithelial) cells from their localization and property. They were derived from pial cells and became potent in the uptake capacity for exogenous substance about at one week after birth. The present study aims to confirm the role of FGP cells and to clarify morphological changes of them in cerebral edema. Cerebral cortices of Wistar rats received head injury (caused with dry ice) were studied electron microscopically at 0.5, 2, 5, 10, 16, 30, 48 and 72 hours after the injury. At the same interval, HRP (horseradish peroxidase) was injected intravenously for the demonstration of uptake capacity of FGP cells. The authors' attention focused on the change of ultrastructure of vascular wall including perivascular phagocytic FGP cell around small blood vessels and on the uptake capacity of FGP cells at each time. From 2 to 5 hours after the cold injury, pinocytotic vesicles often appeared in endothelium and smooth muscle cells, and blood plasma infiltrated into the perivascular space and was taken in the FGP cells. The FGP cells in control were provided with intense round inclusion bodies and looked moderately intense. However, the FGP cells in the experimental animals after the injury became swollen and vacuolized following the fusion of inclusion bodies and breakdown of their limiting membrane and looked pale owing to presence of vacuoles. Under this condition, the uptake capacity of FGP cells for HRP decreased remarkably, and ACPase which was confined to the inclusion bodies in controls spread diffusely into cytoplasm.(ABSTRACT TRUNCATED AT 250 WORDS)