Chapter 29 

 Order 3 Microsporidia Balbiani 



THE Microsporidia are far more widely distributed as parasites 

 among various animal phyla than the Myxosporidia. They 

 are however typically parasites of arthropods and fishes. All Micro- 

 sporidia invade and undergo asexual division and sporogony within 

 the host cell. These infected cells may show frequently an enormous 



Fig. 287. Effects of microsporidian infections upon host animals, a, the 

 central nervous system of Lophius piscatoris infected by Nosema lophii 

 (Doflein); b, a smelt infected by Glugea hertwigi, Xf (Schrader); c, a 

 Culex larva infected by Thelohania opacita, X14 (Kudo); d, a Simulium 

 larva infected by T. multispora, X10 (Strickland); e, portion of testis of 

 Barbus barbus infected by Plistophora longifdis, X1.4 (Schuberg); f, g, 

 normal and hypertrophied nuclei of the adipose tissue cells of larval 

 Culex pipiens, the latter due to a heavy infection by StempelKa magna, 

 X1330 (Kudo). 



hypertrophy of both the cytoplasmic body and nuclei (Figs. 287, /, g; 

 290, a-e), a characteristic feature of the host reaction toward this 

 particular group of protozoan parasites. 



The microsporidian spore is on the whole relatively small as com- 

 pared with that of Myxosporidia. In the vast majority it measures 

 3-6/i in the largest diameter. The chitinous spore membrane which is 

 apparently of a single piece except in a few species, envelops the 



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