Chapter 29 

 Order 3 Microsporidia Balbiani 



THE Microsporidia are far more widely distributed as parasites 

 among various animal phyla than are the Myxosporidia. They 

 are, however, typically parasites of arthropods and fishes. Aside 

 from 1 or 2 species, all Microsporidia invade and destroy host cells. 

 Frequently these infected cells may show enormous hypertrophy of 

 both the cytoplasmic body and the nuclei (Fig. 255), a character- 

 istic feature of the host reaction toward this particular group of 

 protozoan parasites. 



Fig. 255. Effects of microsporidian infection upon hosts, a, the central 

 nervous system of Lophius piscatoris infected by Nosema lophii (Doflein); 

 b, a smelt infected by Glugea hertwigi (Schrader) ; c, larva of Culex territans 

 infected by Thelohania opacita, XlO (Kudo); d, a Simulium larva in- 

 fected by T. multispora, X8 (Strickland); e, part of testis of Barbus barhus 

 infected by Plistophora longifilis, X 1 (Schuberg) ; f , g, normal and hyper- 

 trophied nucleus of adipose tissue of larval Ci lex pipiens, the latter due to 

 infection by Stempellia magna, XlOOO (Kudo). 



The microsporidian spore is relatively small. In the vast majority 

 it meastures 3-6m long. The spore membrane, which is apparently 

 of a single piece, envelops the sporoplasm and the polar filament, a 

 very long and fine filament. The latter may directly be coiled in the 

 spore or may be encased within a polar capsule which is similar to 

 that of a myxosporidian or actinomyxidian spore in structure, but 

 which is mostly obscure in vivo, because of the minuteness of the 

 object. 



When such spores are taken into the digestive tract of a specific 



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