The development of cysts of Blastocystis hominis isolated from human feces
by the Ficoll-Paque concentration method and cultured in Jones' medium cont
aining 10% horse serum is described. The morphological changes were studied
by light and transmission electron microscopy at different intervals for u
p to 48 h. The cysts developed into a large number of vacuolar forms within
24 h, and binary fission was the only mode of reproduction observed.