238 OVINE CASEOUS LYMPH-ADENITIS 



§ 170. Morbid anatomy. The principal lesions are 

 confined, according to the various descriptions, especially that 

 by Norgaard and Mohler, to the lymphatic glands. In many 

 cases only a single gland is affected. The relative frequency 

 with which the various glands become the seat of the lesions 



Fig. 57. Thelegofa rabbit showing enlarged glands after inoctUation 

 with the Bacterium of Preisz {Nurgaard and Mohler). 



may be given as follows : prescapular, precrural, superficial 

 inguinal, bronchial, mediastinal, sub-lumbar, deep inguinal, 

 and scrotal. Rarely the suprasternal and mesenteric glands 

 are affected. Sivori mentions the mesenteric glands among 

 those frequently affected. He fails, however, to mention the 

 mesenteric glands as the seat of lesions in the detailed descrip- 

 tion of twelve typical cases of caseous broncho- pneumonia 

 caused by the bacillus of Preisz. 



When fir.st invaded by the bacterium, the adenoid tissue 

 becomes hyperplastic and the gland enlarges to several times 

 its original size. On section the surface is found to be watery, 

 but otherwise the tissue retains its normal appearance. This 

 is followed by the formation of various centers of degeneration 

 which show concentric layers and gradually become confluent. 

 Finally, the total volume of the gland is transformed into a 

 homogeneous, caseous mass. At the same time the distended 

 capsule increases in thickness and forms a sac which confines 

 the semifluid, grumous mass. In rare instances the sac rup- 

 tures and when close to the surface the contents will be dis- 

 charged. Under ordinary circumstances, the caseous contents 



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