Sporozoa 293 



Fig. 6. 14. A. Oocyst of the Eiiueria-type, with heavy ectocyst and thin 

 endocyst; thin area in the ectocyst is the region of the micropyle; the zygote 

 is undivided; diagrammatic (after Goodrich). B, C. Ovivora thalassemae, 

 x500 (after Mackinnon and Ray): development of sporoblasts (B); oocyst 

 containing sporoblasts (C). D. Oocyst of Aggregata eberthi, portion of a 

 section; nuclei are arranged at the surfaces of folds in the plasmodial mass, 

 shortly before the production of many sporoblasts; x305 (after Dobell). E. 

 Sporozoites formed within sporocysts in oocyst of Eimeria vison; xl620 (after 

 Levine). F-H. Oocysts containing sporozoites not enclosed in sporocysts: 

 Legerella parva (F), xl440 (after Noller); Haemogregarina stepanowi (G), 

 xl890 (after Reichenow); Pfeifjerinella impudica (H), xl560 (after Leger 

 and Holland). 



more layers (Fig. 6. 14, A). The mature macrogamete of Eimeria stiedae 

 (Fig. 6. 18, E, F) contains a peripheral zone of globular inclusions which 

 are extruded to form an ectocyst, continuous except for a micropyle (a 

 minute opening through which the microgamete will enter). After syn- 

 gamy the micropyle is closed by the secretion of more material but the 

 closed area remains thinner than the rest of the ectocyst in certain species. 

 Before the zygote rounds up, a relatively thin endocyst (Fig. 6. 14, A) is 

 secreted within the ectocyst (38). Three layers have been described in 

 Eimeria intricata (44) — a thin transparent outer layer, thickened as a 



