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Unique ultrastructural adaptations of Pseudodiplorchis americanus (Polystomatidae: Monogenea) to a sequence of hostile conditions following host infection

Published online by Cambridge University Press:  06 April 2009

J. Cable  and
R. C. Tinsley
J. Cable
Affiliation:
School of Biological Sciences, Queen Mary and Westfield College, University of London, Mile End Road, London E1 4NS
R. C. Tinsley
Affiliation:
School of Biological Sciences, Queen Mary and Westfield College, University of London, Mile End Road, London E1 4NS
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Summary

The polystomatid Pseudodiplorchis americanus occupies a wider range of habitats and experiences more diverse physiological conditions than any other monogenean. It initially invades the respiratory system of an anuran, Scaphiopus couchii, and then migrates along the alimentary tract while the host is actively feeding, resulting in exposure to digestive enzymes and the surfactant action of bile. Whilst in the urinary bladder, parasites are exposed to wide osmotic fluctuations. This ultrastructural study reveals a set of adaptations unknown elsewhere in platyhelminth biology. During development within the respiratory tract, pre-migratory worms accumulate two types of electron-dense tegumental vesicle. Migration through the gut is accompanied by mass secretion of vesicles which appear to provide protection against digestion. Pre-migrants transferred experimentally to digestive fluids die within minutes unless they have received a specific cue which is responsible for triggering vesicle secretion. Migrants stimulated by this trigger factor can tolerate the same conditions for up to 8 h by continually releasing vesicles to form a protective surface coat. No specific structural adaptations were evident for survival in the lungs or bladder of the host.

Keywords

MonogeneaPolystomatidaeultrastructuretegument
Type
Research Article
Information
Parasitology , Volume 105 , Issue 2 , October 1992 , pp. 229 - 241
Copyright
Copyright © Cambridge University Press 1992

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