Morphological Features and In Vitro Cytopathic Effect of Acanthamoeba griffini Trophozoites Isolated from a Clinical Case
Transmission electron microscopy ((a)–(e)) and scanning electron microscopy (f) of A. griffini trophozoites. (a) Low magnification of an amoeba which shows an extremely irregular profile and a large clearly defined granular round nucleus with a circular electron-dense nucleolus. Numerous digestive vacuoles (Dv) with fibrogranular content and a water expulsion vacuole (Wev) are also observed. The plasma membrane presents its classical three-layered structure (insert). Bar = 2 μm. Insert = 0.1 μm. (b) The nuclear envelope is composed of a double membrane with abundant ribosomes on the external side of the envelope. Bar = 0.2 μm. Insert = 0.1 μm. (c) Mitochondria (M) and numerous profiles of rough endoplasmic reticulum (Rer) located near the edge of the cell were clearly defined. Bar = 0.2 μm. (d) Golgi system with various stacked cisternae. Some membrane-bound vesicles were present in the concave area (asterisks). Bar = 0.2 μm. (e) Fibrogranular matrix located in the periphery of a trophozoite. The asterisk indicates a similar region observed at high magnification where abundant actin filaments are observed. Bar = 1.0 μm. Insert = 0.2 μm. (f) A trophozoite in a lateral view is shown in a displacing position with a portion of the cell body facing upwards. The rough and extremely uneven cell surface exhibits abundant cytoplasmic projections, mostly in the manner of filopodia. Bar = 1.0 μm.