110 MASTITIS OF THE COW 



nective tissue forms. This structure constitutes the pri- 

 mary actinomycoma (Fig. 28). 



The wall of cells of an actinomycoma often presents two 

 different layers: 



1. An internal thin layer of lymphocytes showing little 

 protoplasm and large round nuclei rich in chromatin. 



2. An external thicker layer of epithelioidal connective- 

 tissue cells showing oval vesicular nuclei poor in chromatin, 

 but with considerable protoplasm. 



In the centre of the focus the fungus gradually develops 

 into a characteristic ray fungus colony. The adjacent part 

 of the zone of cells surrounding the 

 fungus undergoes necrosis, but this is 

 corrected by the emigration of fresh 

 cells to replace them. The formation 

 of actinomyces colonies develops 

 slowly. 



Distribution. — The infection 

 ^ „„ . . . , shows a tendency toward metastasis. 



Fia. 28. — Actinomycosis of '' . . , 



i50)"'^'^An^*ovT''actinomyi:^ Mctastasis m actmomycosis is de- 

 Ltor"y"iie"iTeESi cidcdly Icss frcqucut than in tuber- 



visible in the swollen intralo- «nl/-vorc 

 bular connective tissue. The CUlOala. 



act'nom/comareriracoS ExtcnsiOU of thc COUditioU is 



of interlobular connective tissue. • • n • i t> i j." 



prmapally regional. i3y leucocytic 

 transportation a single fungus cell of a colony forms a 

 daughter actinomycoma in the neighborhood of the pri- 

 mary actinomycoma. This local metastasis usually occurs 

 in the direction of the lymph-stream. 



Finally the actinomyces fungus can penetrate the hrniph- 

 vessels, be carried to the supramammary lymph-glands and 

 thus by lymphogenous metastasis produce new actinomy- 

 cotic foci. This metastasis to the lymph-glands appears 

 to take a very long time. Of four udders received the 

 lymph-glands were still attached. In only one case was 

 the lymph-gland on the side of the udder affected swollen 

 and actinomycotic. This udder showed very old actinomy- 



