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An ultrastructural examination of irradiated, immunizing schistosomula of Schistosoma mansoni during their extended stay in the lungs

Published online by Cambridge University Press:  06 April 2009

Avis Mastin
Affiliation:
Department of Biology, University of York, York YO1 5DD
Q. D. Bickle
Affiliation:
Winches Farm Field Station, London School of Hygiene and Tropical Medicine, Hatfield Road, St Albans, Herts.
R. A. Wilson
Affiliation:
Department of Biology, University of York, York YO1 5DD

Extract

An ultrastructural study has been performed on radiation-attenuated parasites fixed in situ during their extended stay in the lungs. At day 7 post-infection all parasites were located within blood vessels. In contrast to normally migrating parasites, at days 13 and 21 post-infection the majority of radiation-attenuated parasites were lying free within alveoli. As far as could be seen, radiation-attenuated parasites had undergone the normal develop mental changes associated with the lung stage of migration. These included elongation of the body and loss of mid-body spines and the fibrous layer beneath the tegument. No ultrastructural evidence was found to suggest why schistosomula failed to migrate further and instead burst into alveoli. No parasites observed on day 7 post-infection were associated with a host inflammatory reaction. At day 13, inflammation was noticeable but could have been a response as much to pulmonary tissue damage as to the presence of parasites. At day 21 post-infection some parasites were internally disrupted but were not associated with host inflammatory reactions and had intact tegumental surfaces – all facts consistent with death by autophagy. One parasite was observed at day 21 with an adherent neutrophil infiltrate and extensive tegumental damage. The relevance of persisting lung-stage parasites to the induction of resistance to challenge is discussed.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1985

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References

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