Brain

This is a section of outer brain cortex, with the brain surface (meninges) at top right. Note the association of F4/80-positive macrophage processes with the meningeal vessel. The cells are commonly cut in cross section reflecting the fact that they spread lengthways along the blood vessels. Within the brain parenchyma, there are numerous very fine processes of microglial cells. They are so ramified that cell bodies are seldom seen.