A cyst-like stage of Blastocystis hominis.

A cyst-like form of Blastocystis hominis is described in stools and in culture. This form is more common in stored stools than fresh material. A cyst wall is secreted under the surface coat of the cell, and the surface coat and cell debris subsequently separate from the cyst. Whether this stage can withstand adverse environmental conditions and is infective to a new host remain to be determined.