Structure and composition of the oocyst wall of Eimeria tenella.

Oocyst walls were purified from unsporulated oocysts of Eimeria tenella. Analysis of the purified material indicated a composition of 67% peptide, 14% lipid, and 19% carbohydrate. The likely physical arrangement of the components places the lipid in a 10 nm thick outer layer, covering a 90 nm thick layer of glycoprotein. The protein component of the structure was dissociated using thiol reagents under denaturing conditions, and was shown to consist of a repeating subunit of approximately 10,000 daltons. The results suggest an explanation for the physical and mechanical resistance of the oocyst wall, as well as possible mechanisms for excystation of sporulated oocysts.