Original Paper

Parasitology Research

, Volume 81, Issue 6, pp 465-469

First online:

Ultrastructure ofBlastocystis hominis cysts

  • V. ZamanAffiliated withDepartment of Microbiology, Aga Khan University
  • , J. HoweAffiliated withDepartment of Microbiology, National University of Singapore
  • , M. NgAffiliated withDepartment of Microbiology, National University of Singapore

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Blastocystis hominis cysts were concentrated from human faeces by repeated washing in distilled water and centrifugation on Ficoll-Paque. This procedure gave a concentrated suspension of cysts without yielding any non-cystic forms. The cysts were examined by both transmission (TEM) and scanning electron microscopy (SEM). Cysts were surrounded by a fibrillar layer that appeared porous in SEM. Many naked cysts without the fibrillar layer were also visible in SEM. They were variable in shape but mostly circular to oval. The diameter of the cyst without the fibrillar layer was 3.5 μm in both TEM and SEM. The nuclear structure was typical ofBlastocystis and exhibited multiple mitochondria with poorly developed cristae. Glycogen was present in small to large clumps in the cytoplasm. The cyst wall was 5–100 nm thick and was bounded internally by an electron-dense plasmalemma.