Fig. 1.

Morphological transformation of trophozoites to cysts (encystation). Upper panel (a–d): differential interference contrast (DIC) images of non-encysting and encysting trophozoites and water-resistant cysts. As encystation progresses, trophozoites become round shaped in the late-encysting phase and finally form cysts. Middle panel (e–h): The biogenesis of encystation-specific vesicles (ESVs) (red) is visible in the early and late encystation stages. The ESVs, which are more numerous in the late stages, are preparing to be fused with the plasma membrane (PM). and form a cyst wall (CW). Bar: 5 µm. Lower panel (i–j): Transmission electron micrographs representing a nascent ESV attached to the endoplasmic reticulum (ER) lumen and mature ESVs transported to the plasma membranes. Bar: 500 nm. FL flagella, VD ventral disc