Fig. 3.

A proposed model to show behavior of cells in injured brain. In the damage core, not only neurons but microglia and astrocytes die. Then, neutrophils infiltrate the brain when there is a sign of infection. Monocytes infiltrate and function to repair damage sites. In the penumbra region where neuronal death does not occur, microglia and astrocytes are morphologically activated and isolate damage sites (Penumbra case I). In the penumbra region where secondary neuronal death occurs, microglia and astrocytes die rather than earlier than neurons (Penumbra case II).