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Amebae Inhabiting
the Aleimentary Canal
Chapter 11
By Beaver
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Introduction:
From the Subphylum Sarcodina Superclass: Rhizopoda
Order: Ameobida
General Characteristics:
1. Small , microscopic in size.
2. Have amoeboid motion.
3. Lack contractile vacoules
4. Multiply through binary fission
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5. Undergo encystation during unfavorable
condition.
6.It has a pseudopodium as the locomotory
organ.
In the genera of Entamoebidae are
differentiated by:
= nuclear structure
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Genus : Entameobidae
Spherical nucleus
Distinct nuclear membrane lined with
chromatin granules.
Small karyosomes.
Generally the trophozoite has single
nucleus.
Natural parasites of the alimentary
canal in most vertebrates.
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Entamoeba histolytica
Synonyms :
-Amoeba coli
- Amoeba dysenteriae- Entamoeba dysenteriae
- Entamoeba terragena
- Endameoba histolytica- Endameoba dysenteria
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General Characteristics:
1. Have successive stages: trophozoite,precyst, cyst, metacyst and metacystictrophozoite.
2. Movement results from long finger-likeor rounded pseudupodial extensionsthat progressively in one direction.
3. Nucleus is spherical, with a diameter
about one fifth of the entire amoeba.4. The active (trophozoite) stage exists only
in the host and in fresh loose feces
http://en.wikipedia.org/wiki/Trophozoitehttp://en.wikipedia.org/wiki/Trophozoite -
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5. cystssurvive outside the host in water,
soils and on foods, especially under moistconditions on the latter.
6. Mode of entry is through ingestion of
contaminated food and water.
7. Ring and dot' appearance: peripheral
chromatin and central karyosome
8. 4 visible nuclei
http://en.wikipedia.org/wiki/Cysthttp://en.wikipedia.org/wiki/Cyst -
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Cyst
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Trophozoite stage
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Life Cycle
Infection occurs by ingestion of cysts (generallyfrom fecally contaminated food or water)
Excystation occurs in the ileum of the smallintestine
Trophozoites multiply by binary fission in thelarge intestine. Most remain in the lumen of theintestine, however, some may invade theintestinal mucosa, enter the bloodstream and
develop in extraintestinal sites. Symptoms Cyst formation is triggered by the dehydration of
gut contents in asymptomatic carriers.
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Asymptomatic
Amebiasis is a disease caused by a one-
celled parasite called Entamoebahistolytica (ent-a-ME-ba his-to-LI-ti-ka).
If trophozoites penetrate the intestinal wall,
serious problems can occur, including liverabcesses, or spread to the lungs and
brain, usually resulting in death.
Symptoms/Pathology
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Pathogenesis
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Vegetative trophozoite stage
size: 4-12 micrometer
motility: active directionalpseudopodia : fingered shape
rapidly extruded
Inlcusions : Bacteria and othermaterial no corpuscles
nucleus : invisible
Entamoeba hartmanni
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Common names
Entamoeba tenuis
Entamoeba minuta
Entamoeba minutissima
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cyst
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Entamoeba coli
Known as:
-Amoeba coli
- Endamoeba hominis
- Loschia coli
- Councilmania lafleuri
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small cyst with one visible nucleus.
The nucleus shows the peripheralchromatin and a central karyosome
trophozoites (4-11 m) are similar to
E.histolyticatrophozoites, present a smallkaryosome often eccentrical.
Resembles E.histolytica
Small raceAsymptomatic to humans
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is a non-pathogenic speciesof Entamoeba
that frequently exists as a commensalparasitein the human gastrointestinal
tract.
trophozoites measure 20-30 m and havea vescicolous nucleus with a large
eccentric karyosome
irregulary distributed peripheral chromatin. The cytoplasm is vacuolated containing
bacteria and yeast
http://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Entamoebahttp://en.wikipedia.org/wiki/Commensalhttp://en.wikipedia.org/wiki/Parasitehttp://en.wikipedia.org/wiki/Gastrointestinal_tracthttp://en.wikipedia.org/wiki/Gastrointestinal_tracthttp://en.wikipedia.org/wiki/Gastrointestinal_tracthttp://en.wikipedia.org/wiki/Gastrointestinal_tracthttp://en.wikipedia.org/wiki/Parasitehttp://en.wikipedia.org/wiki/Commensalhttp://en.wikipedia.org/wiki/Entamoebahttp://en.wikipedia.org/wiki/Species -
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Similar life cycle with E. histolytica
C t
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Cyst
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trophozoite
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