TRICHINELLA SPIRALIS : DEVELOPMENT 



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only in the transversely striated muscular system ; the young 

 nematodes penetrate the capillaries, attain the intra-muscular 

 connective tissue and then invade the transversely striated muscular 

 fibres (Virchow, Leuckart, Graham 1 ). On the ninth or tenth day 

 after infection the first trichinellae have reached their destination ; 

 but further invasions are constantly taking place because the 

 intestinal trichinellae live from five to seven weeks and continue, to 

 produce their young. 



A. 



B. 



FIG. 207. A. Isolated muscular fibre of a rat, invaded by trichinella, 

 510/1. B. Section through the muscle of a rat; the infected fibre has lost its 

 transverse striation ; its nuclei are enlarged and multiplied, 310/1. C. Portion of 

 a trichinella-capsule, at the pole of which connective-tissue cells are penetrating 

 the thickened sarcolemma. (After Hertwig-Graham.) 



The invasion of the muscles by numerous active worms causes more or 

 less severe inflammation in man, which is manifested by fever, by pain 

 in the muscles, and more particularly by muscular contracture ; masticatory, 

 respiratory, and swallowing movements are rendered difficult, and in con- 



1 Trichinellce that are unable to penetrate into muscular fibres invariably die off, 

 no matter where else they settle ; their occurrence in the adipose tissue is disputed, 

 but is still possibly correct, as bundles of muscles are present in the fat of bacon. The 

 trichinellae do not settle in the myocardium, although they may reach it in cases of 

 heavy infection ; they then die off or wander into the pericardium, and eventually into 

 the cavities of the heart. 



