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Ultrastructural changes during in vitro encystment of Blastocystis hominis
1Department of Microbiology, Faculty of Medicine, National University of Singapore, Kent Ridge.
Abstract:
The morphological changes occurring in Blastocystis hominis at different time points following in vitro encystment were studied by electron microscopy. The following stages of the parasite were sequentially seen: (a) the amoebic form, which was irregular in shape, with a majority of the organelles being concentrated at the condensed cytoplasmic region; (b) the pre-cystic form, which was rounded and had an electron-dense material forming a homogeneous wall around the central body; and (c) the cystic form, which had a very prominent, thick osmiophilic electron-dense wall, within which there were many inclusions and possibly reproductive granules. The amoebic form appeared to be an intermediate stage between the vacuolar form and the pre-cystic form, as this stage allowed the parasite to ingest bacteria to enhance encystment. The pre-cystic stage had previously been shown in experimental infection to be infective. The role of the cystic stage in producing infection is currently being investigated.
Insights
This study details the morphological changes of Blastocystis hominis during in vitro encystment. It identifies amoebic, pre-cystic, and cystic forms, revealing insights into parasite development and infectivity.
Area of Science:
- Microbiology
- Parasitology
- Cell Biology
Background:
- Blastocystis hominis is a common intestinal parasite.
- Understanding its life cycle, particularly encystment, is crucial for controlling its transmission.
Purpose of the Study:
- To investigate the morphological transformations of Blastocystis hominis during in vitro encystment.
- To characterize the distinct stages of Blastocystis hominis encystment.
Main Methods:
- Electron microscopy was employed to observe morphological changes.
- Parasites were studied at various time points during in vitro encystment.
Main Results:
- Three sequential stages were identified: amoebic, pre-cystic, and cystic forms.
- The amoebic form, an intermediate stage, facilitates bacterial ingestion for encystment.
- The pre-cystic form was previously identified as infective, while the cystic stage's role is under investigation.
Conclusions:
- The study elucidates the sequential morphological changes during Blastocystis hominis encystment.
- The findings contribute to understanding the parasite's developmental stages and potential infectivity.