Tridimensional observation of fluorescent granular perithelial (FGP) cells in rat cerebral blood vessels.

The tridimensional appearance and distribution of FGP (fluorescent granular perithelial) cells was studied by means of light and scanning electron microscopy. In young rats they first appeared as hexagonal cells in that were closely associated; later they transformed into slender forms and were loosely arranged. Scanning electron microscope observation gave a general view of FGP cells, their globular vacuolated inclusions, and their hypertrophied protrusion into the luminal surface of blood vessels. The nodular protrusions may be related to the limitation of blood flow in small cerebral blood vessels.