[Studies on ultrastructural changes in perivascular cells (F.G.P.) of small cerebral vessels at the initial stage after cold injury--chronological observations on F.G.P. within 24 hours].

As the potentiated cells in reaction to cerebral edema and damage, microglia, astrocytes and macrophages had been listed. Recent neuropathological study elucidated that most of cerebral macrophages were derived from blood leucocytes including monocytes. Several years ago, one of the authors reported the presence of histiocytic cells in perivascular space and named them as fluorescent granular perithelial (F.G.P.) cells from their morphological characteristics. The present paper is concerned with the response of the F.G.P. cells to the vasogenic edema induced with cold injury. The animals employed were Wistar male rats aged 3 months. At 2, 6, 10, and 24 hours after the cold injury, cerebral cortex was excised, and specimens were prepared for light and electron microscopical observations. As already reported, the F.G.P. cells included autofluorescent and PAS positive granules. The intracellular granules were rich in hydrolytic enzymes and lack in sudanophile substances. The F.G.P. cells were derived from leptomeningeal cells and acquired uptake capacity for exo- and endogenous substance after birth. In this paper, the F.G.P. cells locating in the boundary between cold injured and healthy regions were observed. At 2 to 10 hours after cold injury, the F.G.P. cells were vacuolated and swollen, and the electron opacity of them decreased moderately. Lipoidal substance appeared in the intracellular granules first at 2 hours and then increased, while the activity of acid phosphatase in them became low in corresponding with a time interval after the cold injury. At this period, occasionally the F.G.P. cells possessed a complicated boundary to astrocytes surrounding them. In general, such morphological changes were reversible and recovered partially around at 24 hours.(ABSTRACT TRUNCATED AT 250 WORDS)