The ultrastructure of the lodamoeba butschlii cyst from human feces wa
s studied. The glycogen mass appears as a compact dense body in the cy
toplasm without any surrounding membrane. The cytoplasm has no mitocho
ndrion. The nucleus shows a distinct nucleolus filled with electron-de
nse particles. On one side of the nucleolus are electron-dense cytopla
smic masses measuring 200-400 nm. The nuclear membrane is two-layered
and shows pores.