TUBERCULOSIS. 



377 



The giant cells, which are more or less central, have been described 

 as sending off processes, which, by dividing and subdividing, and 





Fici. 162. — Peimary Tubercle of Lung two to theee weeks old, x 50 : 

 «, Portion of wall of a branch of the pulmonary artery ; ^,Z/, giant cella with 

 concentric arrangement of fibrous tissue ; c, centre of tubercle beginning to 

 caseate ; ri, small branch of pulmonary artery seen on transverse section ; 

 ^■, injected capillaries of the alveolar walls (Hamilton'). 



interlacing, form a reticulum, or 

 meshwork. Towards the peripliery 

 of the tubercle the reticulum may 

 become arranged in the form of a 

 capsule as the age of the tubercle 

 advances, and the reticular giant 

 cell becomes eventually converted 

 into fibrous tissue. The bacillus has 

 disappeared, and the tubercle has 

 healed. 



Giant cells cannot be relied upon 

 to indicate tuberculosis. They are 

 not always present in tiibercu- 

 losis, and they are not peculiar to 

 tubercle, being found, for example, 

 in actinomycosis. The only certain 

 indication of tuberculosis is the pre- 

 sence of the tubercle bacillus, which 



Fig. 163.— Laege Oval Giant Cell 

 fkom tubekcle of lung x 300 '■ 

 a, Granular centre; 6, nucleated 

 periphery forming a mantle-like 

 sheath ; c, processes from the 

 same. 



