Figure 14-10.

Responses of Glial Cells to Injury in H&E-Stained Central Nervous System (CNS) Sections.

A, White matter. In nondiseased states, oligodendroglia in white matter are often arranged linearly (interfascicular oligodendroglia) (arrow) and are responsible for the formation of myelin around axons. In gray matter (not shown; see Fig. 14-17), oligodendroglia are dispersed as individual cells around neuronal cell bodies as perineuronal satellite cells (B). H&E stain. B, Gray matter. When neurons are injured or there exists some perturbation of the perineuronal microenvironment, oligodendroglia around neurons can hypertrophy and proliferate in a process referred to as satellitosis. Perineuronal satellite oligodendroglia (arrows) surround a small degenerate neuron with condensed chromatin and little cytoplasm. H&E stain. C, White matter. Astrocytes (arrows) and oligodendroglia (arrowheads) have a limited repertoire of responses to injury in the CNS. Astrocytic proliferation can occur but is very difficult to determine in sections stained with H&E. Here, astrocyte nuclei are somewhat enlarged and appear more numerous than expected. H&E stain. D, Gray matter. Astrocytes respond to injury in hyperammonemia, such as occurs with hepatic encephalopathy, by forming astrocytes with enlarged, markedly vesicular (“watery”), often elongated nuclei called Alzheimer's type II astrocytes (arrows). This type of astrocyte may occur in pairs that are surrounded by a clear space indicative of cellular swelling. H&E stain.

(A courtesy Dr. M.D. McGavin, College of Veterinary Medicine, University of Tennessee. B to D courtesy Dr. J.F. Zachary, College of Veterinary Medicine, University of Illinois.)