As disease severity increases, however, microglia decrease in number and disintegrate; numerous dead CD11b+ cells were found in the ischemic core at 72 h after stroke [46], and, similarly, CD11b+ cells showed disintegration in the ischemic core at 7 days after permanent focal cerebral ischemia induced by photochemically induced thrombosis (PIT) method or middle cerebral artery occlusion (MCAO), whereas there are an increased number of microglia and macrophages in the penumbra [47, 48]. This evidence concerns the gene ITGAM and stroke disorder.