Figure 4: Scanning electron microscopy of the interaction of A. castellanii with MDCK epithelial cell monolayer. After 1 h of interaction, alone (a) or in group (b) trophozoites were observed penetrating the MDCK monolayer. Typical acanthopodia were clearly seen (arrows). Bar = 10 μm. (c) In another area one trophozoite penetrated the monolayer and formed a protuberance on the surface. (d) By the second hour, numerous trophozoites were seen adhered to the monolayer apparently phagocyting a MDCK cell. Bar = 10 μm. (e) Clearly damaged areas of the cell monolayer were observed 3 h after interaction. Several regions of the substrate became apparent as a consequence of the detachment and/or ingestion of the MDCK cells by the amoebae. Bar = 20 μm. (f) Trophozoite apparently phagocyting a portion of an MDCK cell. Bar = 20 μm.