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Maturation of the scolex syncytium in the metacestode of Hymenolepis diminuta, with special reference to microthrix formation

Published online by Cambridge University Press:  06 April 2009

K. Sylvia Richards  and
C. Arme
K. Sylvia Richards
Affiliation:
Parasitology Research Laboratory, Department of Biological Sciences, University of Keele, Keele, Staffs. ST5 5BG
C. Arme
Affiliation:
Parasitology Research Laboratory, Department of Biological Sciences, University of Keele, Keele, Staffs. ST5 5BG
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Summary

The entire surface of the early developmental stages of the cysticercoid of Hymenolepis diminuta bears microvilli. Posteriad differentiation produces a microthrix-bearing surface on the presumptive scolex region, commencing before scolex retraction in cysticercoids in Tenebrio molitor kept at 26°C. During sucker development, the scolex syncytial cytoplasm possesses electron-dense discoidal bodies, aligned parallel to the surface. They become associated with the apical membrane, domes are formed and electron-dense spine-like profiles become apparent. Elevation on short shafts follows, and multilaminate baseplates are then discernible. Fewer microvilli are now present and vesicles with asymmetric membranes (denser inner leaflet) occur within the syncytial cytoplasm. Before scolex retraction, this differentiation extends to the level of the suckers; thus the neck, which becomes reflected on retraction, still possesses only microvilli. After retraction, differentiation proceeds rapidly with increased growth of existing microtriches, discoidal bodies possibly contributing to the shaft support material; the reflected neck develops microtriches and the microvilli are shed into the scolex retraction cavity. The ‘asymmetric’ vesicles increase numerically, some fusing with the apical membrane and releasing their contents. Concurrently, apical membrane asymmetry (denser outer leaflet) becomes apparent. The adult-type surface is formed by 3 days post-scolex retraction, coinciding with the earliest time that the metacestode is infective to the final host.

Type
Research Article
Information
Parasitology , Volume 88 , Issue 2 , April 1984 , pp. 341 - 349
Copyright
Copyright © Cambridge University Press 1984

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References

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