Lesions 



715 



that the first irritation caused by the bacillus is followed by multi- 

 plication of the fixed connective-tissue cells of the part. The cells 

 increase in number by karyokinesis, and form a minute cellular 

 collection or primitive tubercle. 



The group of epithelioid cells and lymphocytes constituting. the 

 primitive tubercle scarcely reaches visible proportions before central 

 coagulation-necrosis begins. The cytoplasm of the cells takes on a 

 hyaline character; the chromatin of the nuclei becomes dissolved in 





Fig. 284. — Miliary tubercle of the testicle: a. Zone of epithelioid cells and 

 leucocytes; ft, area of coagulation-necrosis; c, giant cell with its processes; per- 

 ipherally arranged nuclei and necrotic center; d, seminiferous tubule (Cameron, in 

 "International Text-book of Surgery"). 



the nuclear juice and gives a pale but homogeneous appearance to the 

 stained nuclei. As the tubercle grows, large protoplasmic masses — 

 giant cells — which contain many nuclei are formed. They some- 

 times occur near the center, more frequently near the periphery of 

 the lesion. 



Giant cells are not always formed in tubercles, as the necrotic 

 changes are sometimes too rapid and widespread. 



Tubercles are constantly avascular — i.e., in them no new capillary 

 blood-vessels form — and the coagulation-necrosis soon destroys pre- 

 existing capillaries. Avascularity may be a factor in the necrosis 

 of the larger tuberculous masses, though probably playing no im- 



