Über die Fluoreszenz perivasculärer Zellen im Gehirn der Katze

Summary

• 1. Unstained deparaffinized sections through cat brains fixed with Beuin's fluid are examined under the fluorescence microscope. For comparison, other sections of the same material are stained by means of various techniques including the periodic acid Schiff reaction, and examined under the ordinary light microscope.

• 2. In the unstained sections from brains of adult cats numerous cells are found the cytoplasm of which contains a brightly fluorescent material. No such cells are detected in the brains of cats younger than 8 months.

• 3. The fluorescent cells in the brains of adult cats are found not only in most regions of the central nervous system but in the pia mater as well. No fluorescent cells are seen in and around the hypophysis, in the pineal gland, in the lamina terminalis, in the subfornical organ, in the area postrema and in the choroid plexus.

• 4. Within the brain the cells are located in the immediate neighbourhood of capillaries and small blood vessels and in the Virchow-Robin spaces around the larger arteries and veins.

• 5. The fluorescent cells are shown to be identical with cells the cytoplasm of which stains red in sections treated with the periodic acid Schiff reaction. The fact that such cells are already present in the brains of young cats in which the fluorescent material is not yet detectable indicates that this material is different from that staining red with the periodic acid Schiff reaction.

• 6. According to their location the fluorescent cells appear to be derived from typical perivascular microglia cells or from connective tissue cells of the pia mater and of the tissue strands surrounding the blood vessels in the spaces of Virchow and Robin.

• 7. The findings indicate that no fundamental difference exists between perivascular microglia cells, pericytes and macrophages.