50 PRINCIPLES OF VETERINARY SURGERY 



liferation of embryonal connective-tissue cells, in tuberculo- 

 sis, different forms appear than in g-landers. In the former, 

 the tubercle is made up of a central giant cell surrounded by 

 several rows of epithelioidal cells, with a mass of lymphoid 

 cells, encircling the whole. The giant cell has a dense row 

 of nuclei massed together on one border. This character- 

 istic appearance has classified it as the giant cell of tubercu- 

 losis, other giant cells having their nuclei scattered through- 

 out the protoplasm. By a special staining process the tub- 

 ercle bacilli can usually be demonstrated within the giant 

 cells, and also elsewhere in the tissue. 



Large areas of caseation can be seen scattered here and 

 there. They are usually adjacent to the lymphoid cell 

 masses, of which they are a degeneration. The lymphoid 

 tissue is the youngest form of embryonic connective tissue 

 and having almost no blood supply, easily degenerates into 

 caseated areas. The epithelioidal cells are probably an ad- 

 vanced stage of the lymphoid cells, antecedent to fibroblasts, 

 the characteristic cell in most regenerative tissue, but in 

 tuberculosis and glanders, the proliferating tissue is of such 

 a low type that the matured forms of connective tissue cells 

 seldom appear. 



The tubercle of glanders is made up almost wholly of 

 lymphoid cells, and no such regular formation occurs as in 

 that of tuberculosis. Areas of caseation are present and a few 

 epithelioidal cells may be found, but no characteristic giant 

 cells. If the cells have degenerated so that a liquefaction 

 necrosis of the gland occurs, the typical glanders bacilli can 

 be demonstrated by staining a little of the pus. A young 

 tubercle is necessary for the demonstration : in old tubercles, 

 the germs have usually degenerated along with the cells. 



The infectious venereal tumor is a pathological lesion 

 practically limited to dogs, although a similar condition is 

 found in the human. It is most common in the bull dog and 



