Avian Tubc'icLilosis. 



61 ;5 



tissue in.ay contain large, yellowisli-wliite, clieesy foci. Tlie 

 pericardial sac may contain muck fluid while the surface of 

 the heart may be covered with flat, grayish-red, raspberry-like 

 or ahnost wart-like proliferations (Tietz). Among the "other 

 organs, we find, now and tlien, tnlierculous caseous foci on 



Fig. .90. Allan Tuberculosis. 

 intestinal wall. 



Casuatc'd foci in the liver and nodules nn tlio 



the peritoneum, in the kidneys, in the ovaries, in the testicles, 

 in the pericardium and the muscle tissue of the heart, in the 

 air cells, in the gizzard, as well as under the skin and the 

 balls of the feet. 



The histological structure of the avian tubercle is similar in character to 

 that of the maiiiinalian tubercle with the uniuiportant exception, that by far the 

 greater part of it consists of large eiiithelioid cells of the foreign-body giant-cell 

 type containing tubercle bacilli and disposed in radial or wreathlike scal.y fashion 

 (as seen in section) around the central necrotic mass. The degenerative process of 

 the tubercle also corresponds more to the hyaline type. Tubercle bacilli are always 

 jiiesent in large numbers in the fresh tubercles as well as in the cheesy nodules 

 and in the contents of the involved joints. They are readily demonstrated by means 

 of the usual methods of staining (See p. 569). 



