Ultrastructural and lectin-histochemical differences between the scolex/strobila and bladder teguments of the Taenia taeniaeformis strobilocercus

The strobilocercus stage of the cat tapeworm Taenia taeniaeformis is surrou nded by a single syncytial sheet of cytoplasm called the tegument. The oute r membrane of the tegument covers both the scolex/strobila (S/S) and the bl adder portions of the strobilocercus, but only the S/S region is resistant to intestinal digestion. It has been suggested that the glycocalyx, the sur face-exposed glycoconjugates of the outer membrane, may serve to insulate u nderlying surface membrane components from digestion. In this study, we use d lectin binding to test the hypothesis that the glycocalyx of the S/S is d ifferent from that of the bladder and that this may serve as the resistance mechanism of the S/S to digestion. Biotin-labeled lectins and an avidin-gl ucose oxidase detection system were applied to whole strobilocerci and to 1 -mu m epon-araldite plastic-embedded sections. Lectins bound to either both regions of the strobilocerci, to the S/S regions only, or did not bind at all. The restriction of some glycoconjugates to the glycocalyx of the S/S r egion only is consistent with our hypothesis.