Amebae Inhabiting The Aleimentary CanalPresentation Transcript
Amebae Inhabiting the Aleimentary Canal Chapter 11 By Beaver
From the Subphylum Sarcodina
General Characteristics :
1. Small , microscopic in size.
2. Have amoeboid motion.
3. Lack contractile vacoules
4. Multiply through binary fission
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
Genus : Entameobidae
Distinct nuclear membrane lined with chromatin granules.
Generally the trophozoite has single nucleus.
Natural parasites of the alimentary canal in most vertebrates.
- Amoeba coli
- Amoeba dysenteriae
- Entamoeba dysenteriae
- Entamoeba terragena
- Endameoba histolytica
- Endameoba dysenteria
Have successive stages: trophozoite, precyst, cyst, metacyst and metacystic trophozoite.
Movement results from long finger-like or rounded pseudupodial extensions that progressively in one direction.
Nucleus is spherical, with a diameter about one fifth of the entire amoeba.
The active ( trophozoite ) stage exists only in the host and in fresh loose feces
5. cysts survive outside the host in water, soils and on foods, especially under moist conditions 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
Infection occurs by ingestion of cysts (generally from fecally contaminated food or water)
Excystation occurs in the ileum of the small intestine
Trophozoites multiply by binary fission in the large intestine. Most remain in the lumen of the intestine, however, some may invade the intestinal mucosa, enter the bloodstream and develop in extraintestinal sites. Symptoms
Cyst formation is triggered by the dehydration of gut contents in asymptomatic carriers.
Amebiasis is a disease caused by a one-celled parasite called Entamoeba histolytica (ent-a-ME-ba his-to-LI-ti-ka) .
If trophozoites penetrate the intestinal wall, serious problems can occur, including liver abcesses, or spread to the lungs and brain, usually resulting in death.
Vegetative – trophozoite stage
size: 4-12 micrometer
motility: active directional
pseudopodia : fingered shape
Inlcusions : Bacteria and other
material no corpuscles
nucleus : invisible
- Amoeba coli
- Endamoeba hominis
- Loschia coli
- Councilmania lafleuri
small cyst with one visible nucleus. The nucleus shows the peripheral chromatin and a central karyosome
trophozoites (4-11 µm) are similar to E.histolytica trophozoites, present a small karyosome often eccentrical .
Asymptomatic to humans
is a non-pathogenic species of Entamoeba that frequently exists as a commensal parasite in the human gastrointestinal tract .
trophozoites measure 20-30 µm and have a vescicolous nucleus with a large eccentric karyosome
irregulary distributed peripheral chromatin.
The cytoplasm is vacuolated containing bacteria and yeast