Sporozoa 291 



Life-cycles 



An infection is initiated when the host ingests oocysts or sporocysts 

 (spores), or in rare cases, when naked sporozoites are inoculated or in- 

 gested. Each surviving sporozoite enters a tissue cell and develops into a 

 multinucleate schizont. Merogony then occurs. The resulting merozoites 

 enter other cells and repeat the cycle. In typical Coccidia, merogony in- 



_^.,.«flrr^®, 





Fig. 6. 13. A. Merogony in Oi'ivora thalassemae; section of schizont, x500 

 (after Mackinnon and Ray). B-D. Merogony, involving formation of mero- 

 blasts, in Caryotropha mesnili (after Siedlecki): young trophozoite (B); mero- 

 blasts formed by division of a trophozoite (C); formation of merozoites from 

 meroblasts (D); x535. E-G. Production of microgametes in Ovivora thalas- 

 semae; x850 (after Mackinnon and Ray). H. Syzygy in Adelea ovata; xll40 

 (after Shellack and Reichenow). I. Syzygy in Adelina deronis, microgametocyte 

 with four nuclei; xl600 (after Hauschka). J. Zygote of Adelea ovata, oocyst 

 membrane formed, three microgametes left outside; xll40 (after Shellack and 

 Reichenow). K. Flagellate microgamete of Caryotropha mesnili; xl510 (after 

 Siedlecki). 



