Figure 14-55.

Spongiform Encephalopathy (Scrapie), Brain, Motor Neurons, Sheep.

A, Neuronal cell bodies contain one or more discrete and/or coalescing clear vacuoles (V). There are no inflammatory cells in this disease. Similar spongiosis is evident in the neuropil. H&E stain. B, Scrapie, experimental, brain, cerebellum, mouse. The cerebellar granule cells are at the top of the figure. There is notable hypertrophy and proliferation (astrocytosis) of astrocytes and their fibers (astrogliosis) (black branching fibers). Some of the processes (running diagonally across the illustration) end, as is normal for astrocytes, on the walls of capillaries. Cajal's gold sublimate stain for astrocytes.

(A courtesy Dr. D. Gould, College of Veterinary Medicine and Biomedical Sciences, Colorado State University; and Dr. M. McAllister, College of Veterinary Medicine, University of Illinois. B courtesy Dr. W.J. Hadlow.)