► Trophozoite:Trophozoite: Amebic stage Amebic stage characterized by its ability to move, characterized by its ability to move, obtain food and multiply.obtain food and multiply.

►Cyst:Cyst: Amoebic stage characterized by Amoebic stage characterized by a thick cell wall that allows it to a thick cell wall that allows it to survive the environment and survive the environment and transmitted to a healthy hosttransmitted to a healthy host

Entamoeba histolyticaEntamoeba histolyticaTrophozoiteTrophozoite Exhibits progressive motility with finger-like pseudopodia Single nucleus with small compact karyosome that may be placed centrally or eccentrically. Peripheral chromatin is finely granular and distributed evenly over the inner surface of the nuclear membrane. Non-invasive forms may contain bacteria, while invasive forms contain ingested RBC’s.

Entamoeba histolyticaEntamoeba histolyticaCyst:Cyst: Mature cysts are spherical and contain 4 nuclei, while immature forms contain 1-2 nuclei. Glycogen found in mature cysts is usually diffused, and it’s concentrated into a discrete mass in immature ones. If present, chromatoid bodies are usually elongated with bluntly rounded ends.

Entamoeba coliEntamoeba coli

Trphozoite:Trphozoite: Single nucleus with a large non-compact karyosome usually located eccentrically Peripheral chromatin is in the form of coarse granules that may appear as a dark ring material. Cytoplasm is usually vacuolated and may contain bacteria, yeasts, and other debris.

Entamoeba coliEntamoeba coliCyst:Cyst: Usually spherical, but sometimes ovalUsually spherical, but sometimes oval Contain 1 - 8 nuclei with a large irregular Contain 1 - 8 nuclei with a large irregular in shape cytoplasmin shape cytoplasm In mature cysts, the cytoplasm may In mature cysts, the cytoplasm may contain diffuse glycogen while in immature contain diffuse glycogen while in immature cysts the glycogen may be a large discrete cysts the glycogen may be a large discrete mass.mass. Chromatoid bodies are rarely seen and if Chromatoid bodies are rarely seen and if present they are splinter-like with pointed present they are splinter-like with pointed endsends

Naegleria fowleriNaegleria fowleriTrophozoite:Trophozoite: An ameboflagellated form is present, but An ameboflagellated form is present, but only ameboid forms exist in humansonly ameboid forms exist in humansProduce pseudopods that are rounded and Produce pseudopods that are rounded and fingerlike called “lobopodia”.fingerlike called “lobopodia”. Nucleus is large with dense karyosome Nucleus is large with dense karyosome and lacks peripheral chromatin on nuclear and lacks peripheral chromatin on nuclear membrane.membrane.Trophozoites in culture express many Trophozoites in culture express many nucleinuclei Cytoplasm is granular and has abundant Cytoplasm is granular and has abundant vacuoles.vacuoles. Sucker-like structures “amebostomes” Sucker-like structures “amebostomes” might be present.might be present.

Naegleria Naegleria fowlerifowleri

Cyst: Not present in human tissues

In nature, cysts are spherical and have a smooth single-layered wall that have one nucleus with a centrally located karyosome which lacks peripheral chromatin.

Highly resistant to desiccation

Acanthamoeba spp.Acanthamoeba spp.

Trophozoite:Trophozoite: Produce slender, spine-like pseudopods Produce slender, spine-like pseudopods called “acanthopodia”.called “acanthopodia”. Cytoplasm is granular and contains water Cytoplasm is granular and contains water and food vacuoles.and food vacuoles. Single nucleus with a large central Single nucleus with a large central karyosome and a nuclear membrane karyosome and a nuclear membrane lacking chromatin.lacking chromatin.

AcanthamoebaAcanthamoeba spp.spp.Cyst:Cyst: Round with ragged endsRound with ragged ends Cell wall consists of 2 layers: Cell wall consists of 2 layers:

* Wrinkled fibrous outer wall (exocyst)* Wrinkled fibrous outer wall (exocyst)

* Smooth inner wall with diverse morphology * Smooth inner wall with diverse morphology (endocyst)(endocyst)

Single nucleus with a large central karyosomeSingle nucleus with a large central karyosome

Toxoplasma gondiiToxoplasma gondii

Toxoplasma Toxoplasma gondiigondii

Tachyzoite (trophozoite)Tachyzoite (trophozoite) Crescent-shaped organisms with tapered Crescent-shaped organisms with tapered anterior end, a blunt posterior end and a anterior end, a blunt posterior end and a large nucleus.large nucleus. Contains a variety of organelles Contains a variety of organelles (mitochondrion, golgi apparatus), but they (mitochondrion, golgi apparatus), but they are not visibleare not visible

Toxoplasma gondiiToxoplasma gondiiBradyzoiteBradyzoite Smaller than tachyzoitesSmaller than tachyzoites Hundreds of bradyzoites enclose Hundreds of bradyzoites enclose themselves to form a cyst.themselves to form a cyst.

Cyst:Cyst: Spherical in brain and elongated in Spherical in brain and elongated in skeletal and cardiac muscles.skeletal and cardiac muscles. Organisms within the cyst are called Organisms within the cyst are called bradyzoites.bradyzoites.

Cryptosporidium parvumCryptosporidium parvum

Cryptosporidium Cryptosporidium parvumparvum

Oocyst:

Spherical to oval and sporulated when shed in the feces. Sporulated oocyst has a thick colorless wall and contain four sporozoites and numerous granules.

Plasmodium sp.Plasmodium sp.Ring FormRing Form Ring-like appearance, consisting of a blue circle. Ring-like appearance, consisting of a blue circle.

The space inside the ring is known as a vacuoleThe space inside the ring is known as a vacuole

SchizontSchizont 12-24 merozoites occupying majority of the 12-24 merozoites occupying majority of the

RBC. RBC. Merozoites surrounded by cytoplasmic Merozoites surrounded by cytoplasmic

materialmaterial

Plasmodium sp. Plasmodium sp.

Microgametocyte (male)Microgametocyte (male) Consists of a large diffuse mass of chromatin

surrounded by a halo.

Macrogametocyte (female)Macrogametocyte (female) Shape ranges from round, oval, to crescent. Chromatin is compact surrounded by cytoplasmic

material

MicroMicro MacroMacro

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