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?
Astrocytes Endothelial cells Microglial cells Neutrophils