Chapter 28 

 Order 3 Microsporidia Balbian 



THE Microsporidia are far more widely distributed as para- 

 sites 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. 

 218), a characteristic feature of the host reaction toward this 

 particular group of protozoan p9,rasites. 



Fig. 218. Effects of microsporidian infection upon hosts, a, the cen- 

 tral 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 infected by T. multispora, X8 (Strickland); e, part of 

 testis of Barbus barbies infected by Plistophora longifilis, Xl (Schu- 

 berg); f, g, normal and hypertrophied nucleus of adipose tissue of 

 larval Culex pipiens, the latter due to infection by Stempellia magna, 

 XIOOO (Kudo). 



The microsporidian spore is relatively small. In the vast ma- 

 jority it measures 3-6m long. The spore membrane, which is ap- 

 parently 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 



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