MODULE 2 UNIT 2 Flashcards
It includes the amoebas, which have no permanent locomotory organs, but move about with the aid of temporary prolongations of the body called
It includes those protozoa which possess whip-like structures called
Two groups of amoebae are of medical importance.
- Parasitic amoebae; 2. Pathogenic free-living amebae
three genera of Parasitic amoebae
Entamoeba, Endolimax, and Iodamoeba
Parasitic amoebae include
Entamoeba histolytica, Entamoeba dispar, Entamoeba coli, Entamoeba hartmanni, Endolimax nana, and Iodamoeba butschlii which are all found in the intestinal lumen, and Entamoeba gingivalis which is found in the mouth
is the only pathogenic species which causes intestinal and extraintestinal amoebiasis.
E. histolytica
All the other amaebae species are commensals. They all exist in two forms in the life cycle, trophozoites and cysts, EXCEPT {?} which occurs in the trophozoite stage only
E. gingivalis
Several species of free-living amoebae are found in soil and water.
Pathogenic free-living amebae
are of clinical interest because they can cause fatal meningoencephalitis and eye infections.
(1) Naegleria and (2) Acanthamoeba
Trophozoite Size
10-60 µm (ave: 15-20 µm)
Trophozoite Motility and
Pseudopodia
Progressive, rapid, unidirectional motility; with hyaline, fingerlike pseudopodia formed rapidly
Trophozoite Nucleus
Number
1
Trophozoite Peripheral
chromatin
Fine granules, uniform in size and usually evenly distributed; may have beaded appearance
Trophozoite Karyosome
Small, compact, centrally located
Trophozoite Linin network
The space between the karyosome and the nuclear membrane is traversed by fine thread of linin network giving a radial spokeswheel or cartwheel appearance.
Trophozoite Cytoplasm
Appearance
Finely granular, “ground-glass” appearance; clear differentiation into a clear ectoplasm and more granular endoplasm; if present, vacuoles are usually very small
Trophozoite Inclusions
RBCs are diagnostic; few ingested bacteria or debris in vacuoles
Cyst Size
10-20 µm (12-15 µm)
Cyst Shape
Usually spherical
Cyst Nucleus
Number
1-4; mature cyst contains 4 nuclei
Cyst Peripheral chromatin
Similar to that seen in trophozoite
Cyst Karyosome
Similar to that seen in trophozoite
Cyst Cytoplasm
Chromatoidal bodies
May be present; usually elongate with blunt, rounded, smooth ends (cigarshaped); may be round or oval.
Cyst Glycogen vacuole
May be present, usually diffuse, stains reddish brown with iodine.