Scavenger cell in the CNS is:
Microglia is the only cell that is borne out of CNS and moves into the CNS. It is formed from monocyte lineage in the bone marrow. It is physiologically and embryologically unrelated to other neural cell types It has phagocytic function hence known as "scavenger cell" in the CNS.
Astrocytes
Microglia
Oligodendrocyte
Schwann cell
Introduction to Central Nervous System