Amebae Inhabiting the Aleimentary Canal 1201110548758682 4

8/12/2019 Amebae Inhabiting the Aleimentary Canal 1201110548758682 4

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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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Amebae Inhabiting the Aleimentary Canal 1201110548758682 4