Visualization of the cytostome in Trypanosoma cruzi by high resolution field emission scanning electron microscopy using secondary and backscattered electron imaging.

High resolution scanning electron microscopy was used to analyze the surface of epimastigote, amastigote and trypomastigote forms of Trypanosoma cruzi. Significant differences were observed between these forms and in different areas of the same cell. The cytostome found in amastigote and epimastigote forms could be easily visualized in images, which resemble those obtained only using the freeze-fracture technique. In contrast to other areas of the cell surface, the region of the cytostome, localized close to the flagellar pocket, showed a rugous surface and an opening with a diameter of 90 nm. Gold-labeled concanavalin A binds to the whole cell surface. However, the extent of binding was much higher in the region of the cytostome. The results obtained show that high resolution scanning electron microscopy is a powerful technique for analyzing the surface of protozoa.