Figure 14-23.

Gitter Cells, Cerebrum.

A, Early polioencephalomalacia, cow. Note the angular, eosinophilic neurons with pyknotic nuclei (ischemic cell change). Macrophages (arrows) in the perivascular space have been recruited from the circulating monocytes. These cells phagocytose cellular debris from the necrotic neurons and the myelin from the nerve fibers undergoing degeneration after the death of their neurons. Microglia also participate in this phagocytic response. Macrophages that have ingested degenerate myelin or other cellular debris have foamy cytoplasm and are termed gitter cells. H&E stain. B, Previous region of necrosis, dog. The normal brain parenchyma has liquefied, and the debris has been ingested by macrophages (arrows), which has resulted in the cytoplasm of these cells becoming foamy. They are now designated as gitter cells or, simply, foamy macrophages. H&E stain.

(Courtesy Dr. J.F. Zachary, College of Veterinary Medicine, University of Illinois.)