436 BIOLOGY OF THE LABORATORY MOUSE 



rhages, the microscopic picture is one of diffuse necrosis in the liver and 

 spleen. The characteristic feature, however, is the presence of intracyto- 

 plasmic eosinophilic inclusion bodies in the epithelial cells of the intestine 

 and the acinar cells of the pancreas (Fig. i68). These inclusions occur 

 singly or in small groups, and vary in size up to 7 /jl. Only one observer (242) 

 has noted them in the liver. 



The lesions in the chronic or cutaneous type of infection are more exten- 

 sive. Those in the skin consist of crusted, superficial ulcers surrounded by 

 indurated, edematous tissue. Ascites, hydrothorax, and congestion are 



^ present. The liver is a mottled red 

 MP '-'■:4% color and contains numerous greyish- 



white areas of necrosis. The spleen is 

 enlarged and red with similar necrotic 

 areas. Over the peritoneum and 

 serosal surface of the viscera may be 

 found whitish areas suggestive of fat 

 necrosis. The kidneys are usually 

 normal but may be enlarged and pale, 

 resembling those of the second stage of 



i' 



igF 



*'«»!. 



^ ^ *^ •^ nephritis. Microscopic examination 



s^^^ confirms the gross evidence of an exten- 



^^^^ sive necrotizing process which involves 



Fig. 168. — Infectious ectromelia: the skin, liver, spleen, peritoneum, and 



inclusion bodies (black) in cells of the other tissues. Perivascular cufhng and 



pancreas. Mann's stain. (Xiooo.) r ,. j .• j •, 



^^ ,, ^ , JTT-,- , JN fatty degeneration are pronounced m 



(From McGaug/iev and ]] Inte/icad.) , ,. , „ 1 i-i 1 



the liver. Affected kidneys show 



groups of endothehal-like cells in the cortex, small hemorrhages, and fatty 

 degeneration of the convoluted tubules. Intracytoplasmic inclusion bodies 

 are most numerous in the epithelial cells of the skin, where they may be 

 as large as 13 /jl in diameter (Fig. 169). They are also found in connective 

 tissue cells and endothelial cells of vessels in the subcutaneous tissue, 

 epithelial cells of the intestine, acinar cells of the pancreas, secretory 

 cells of the salivary glands, and epitheHal cells of the tongue and 

 lips. The larger inclusions are round or oval in shape, stain evenly 

 with acid dyes, and as they enlarge cause degeneration and finally dis- 

 appearance of the nucleus. For demonstration of the bodies, the tissue 

 may be fixed in a saturated solution of bichloride of mercury containing 

 5 per cent glacial acetic acid, and stained with the ordinary hematoxylin- 

 eosin stain. Mann's methyl blue eosin or acid fuchsin and Weigert hema- 



