Lec 2 - Lab 2- Para- Entamoeba histolytica

Question 1

characteristic feature of trophozoite ?

+ The nucleus, vesicular type, can be clearly seen in the specimen stained with hematoxylin

Answer 1

1-nucleus membrane is delicate but distinct line

2-peripheral chromatin granules are fine and well-distributed on the inner surface of the nuclear membrane.

3-The karyosome is small and centrally located

Question 2

characteristic feature of cyst ?

Answer 2

The characteristics of the cyst nucleus are similar to that of the trophozoite

The other two morphological features are the
1- glycogen vacuole
2- the chromatoid body (or bar).

the glycogen vacuole is the food reservoir
the chromatoid bar has two round and smooth ends.

• Both glycogen vacuole and the chromatoid bar become smaller and smallwares the cyst ages

Question 3

Entamoeba histolytica

Answer 3

1. Trophozoite, active form
2. Cyst, non-motile form and it’s immature and mature

Immature cyst is spherical in shape, about 10 ~20 μm, and has one or two nuclei.

Mature cyst: the shape and size is same as the immature cyst, but it has 4 nuclei.

Question 4

Pathogenic mechanism Of E.histolytica

Answer 4

The pathogenic materials of E. histolytica include

1-lectin, amoebic pore forming
2-protein dissolving enzyme.

The lectin guides the trophozoite to adhere to the intestinal epithelia, neutrophils and RBCs . These pathogenic materials destroy the host’s tissues.

The trophozoite invade the mucosa by producing tiny pinpoit lesions at the site of entry, spread into the submucosa and produce typical flask-shaped ulcer. The ?open of the ulcer toward intestinal lumen looks like a crater

Question 5

About clinical manifestation is Intestinal amoebiasis, Explain that ?

Answer 5

A- Emoebic dysentery is most common form of amoebiasis. The acute case discharges unformed feces several times per day with the pain in right inferior part of the abdomen, nausea, low fever around 38℃, and fatigue. The jam-like stool with foul smell, in which there are great number of trophozoites and Charcot-Leyden crystals.

b. Chronic amebic colitis manifests vague abdomen discomfort, alternation of constipation and dearrhea, stool with mucus and foul smell, nausea, anorexia, fatigues, weight loss.

Question 6

Life cycle of Entamobea histolytica ?

Answer 6

life cycle has two stages:
the motile ameba (trophozoite)
the nonmotile cyst .

The trophozoite is found within the intestinal
extraintestinal lesions
in diarrheal stools.

The cyst predominates in nondiarrheal stools.

The cyst has four nuclei, an important diagnostic criterion.
Upon excystation in the intestinal tract, an ameba with four nuclei emerges and then divides to form eight trophozoites.
The mature trophozoite has
1-a single nucleus
2- lining of peripheral chromatin 3-prominent central nucleolus (karyosome).