INFECTIOUS DISEASES 



221 



of cutaneous infection or it may be transmitted from 

 elsewhere in the body. 



The transmission of the tubercle bacilli from the 

 mother to the fetus is possible but it is of rare occurrence. 

 But a weakened condition or susceptibility to the disease 

 may and frequently is transmitted from the mother to 

 the fetus. 



Lesions. The typical initial lesion of tuberculosis is 

 the tubercle which has been aptly defined as a nonvascular 

 nodule composed of leukocytes, endothelial, giant 

 and connective tissue cells, with a tendency for the 

 central part of the nodule to undergo necrosis. There 



B 



B' 



Fig. 26.- 



A. Normal muscle, 

 in swine. 



-TUBERCULOSIS OF THE TONGUE. 

 B. tuberculous lesions. This is a rare condition 



may be slight variation in the tubercle in different ani- 

 mals, due to variation of susceptibility of the animal and 

 variation of the virulency of the infecting bacilli. The 

 typical lesion may also be materially modified by second- 

 ary lesions. Tuberculous lesions may occur in any tissue 

 or organ, but lymphoid tissue is most frequently affected. 

 The tubercle bacilli and their products are the causa- 

 tive factors in the formation of a tubercle. Having 

 lodged in a tissue favorable for their growth and develop- 

 ment, the bacilli begin to multiply and to eliminate 

 products that stimulate the surrounding connective tissue 

 and endothelial cells to increase in number, and at the 



