Amebiasis Study Guides | University of Wisconsin-Green Bay

University:
University of Wisconsin-Green Bay
Course:
CLS 427 | Clinical Parasitology
Academic year:

2024
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123

Pages:

2
Author:

veroo os2

G. AMEBIASIS G.1 Entamoeba histolytica Entamoeba histolyticahas 2 stages/forms, namely trophozoites which are usually found in watery feces and cysts which can be found in solid feces. On microscopic examination, stool samples are difficult to differentiate fromEntamoebadispar(non-pathogenic), so further tests such as PCR and monoclonal antibodies are needed to be able to differentiate between the two. Trophozoites: - The size varies between 12–60 µm, in liquid and fresh feces, can beLarge trophozoites were found. - The ectoplasm is clear, thick, sometimes pseudopods can be seen that are shaped like fingers. - Granular endoplasm, inside which there are food vacuoles which often contain erythrocytes. - The nucleus is spherical in shape, its diameter is about 1/5–1/6 of the diameter of the entire amoeba, contains small karyosomes located centrally and is connected to the nuclear membrane by fine achromatic fibrils arranged in radials, the inner wall of the nucleus contains a regular accumulation of fine chromatin granules. Cyst: - The shape is usually spherical, subspherical or ovoid, the walls are thin. - The diameter varies between 10 – 20 µm. - Ripe cysts have 4 nuclei which with Iodine staining of the karyosoma are visible as shiny light yellow dots surrounded by a slightly dark yellowish brown nucleoplasm. - In young cysts, in the cytoplasm there are chromatoid objects in the form of rods like sausages with rounded ends, refractive, and colored confused,but in mature cysts the chromatoid objects become blurred or even not visible at all; Glycogen vacuoles can also be seen in young cysts, while they are rarely found in mature cysts. G.2 Entamoeba coli Entamoeba colicommensal life with other intestinal protozoa in the large intestine / colon cavity.The shape of the trophozoites is also similar in size toEntamoeba histolytica. Therefore, even though it is not pathogenic, it is necessary to study its morphology to differentiate it fromEntamoeba histolytica. Trophozoites: - The size varies between 15 – 50 m. - The cytoplasm is granular, the ectoplasm is difficult to distinguish from the endoplasm, with iron - hematoxylin staining, the ectoplasm is relatively non - regularcompared to the endoplasm, the pseudopods are short and wide. - The nucleus is spherical in shape, the nuclear membrane is relatively thick with coarse, irregular chromatin granules with quite large and eccentrically located karyosomes. - Food vacuoles contain bacteria, they do not contain blood cells. Cyst: - Spherical or subspherical in shape, thin walls, diameter varies between 10 – 35 m. - In immature cysts there are pointed chromatoid objects, irregular masses and rather dense glycogen masses with blurred edges; but in mature cysts, the mass of glycogen and chromatoid objects becomes less dense or disappears completely. - Ripe cysts have 8 nuclei, sometimes 16 or more.

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