Fig. 5. Typical microscopic appearance of spleen of animal with advanced runt disease. 

 The normal splenic architecture is greatly distorted and there is a considerable influx of 

 histiocytes. (Haematoxylin and eosin. x 80.) 



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Fig. 6. High-power view of population of cells in the spleen from an animal with 

 advanced runt disease selected to show the typical histiocyte infiltrate. (Haematoxylin and 



eosin. x 400.) 



To face p. 2 s^ 



