An 18-year-old man suffers massive trauma in a motorcycle accident. A CT scan shows multiple intracerebral hemorrhages. The patient expires after 6 months in a coma. At autopsy, there are cystic cavities within the frontal and temporal lobes, corresponding to the areas of prior hemorrhage. These cavities were formed in large measure due to the phagocytic activity of which of the following cell types?

Microglia are phagocytic macrophage-derived cells of the CNS, accounting for 5% of all glial cells. In response to necrosis, macroglia become phagocytic, accumulate lipids and other cellular debris, and are designated gitter cells. Some reactive microglia exhibit a prominent elongated nucleus, in which case they are referred to as rod cells. After microglial phagocytosis, astrocytosis (choice A) then leads to local scar formation, which persists as telltale evidence of a prior injury.Diagnosis: Cerebral contusion