Trophozoite[ edit ] The trophozoites are 9—14 micrometres in diameter. Trophozoites are one of the two forms of I. This form has a pseudopodia for locomotion. The pseudopodia is short and blunt.
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Resources Casual Agents Several species of amebae are capable of colonizing the human gastrointestinal tract but, in contrast to Entamoeba histolytica, are not considered pathogenic. The nonpathogenic intestinal amebae include several Entamoeba species E. Entamoeba species in the E. Both cysts and trophozoites of these species are passed in stool and are considered diagnostic.
Cysts are typically found in formed stool, whereas trophozoites are typically found in diarrheal stool. Intestinal colonization with nonpathogenic amebae occurs after ingestion of mature cysts in fecally contaminated food, water, or fomites.
Excystation occurs in the small intestine ; and trophozoites are released, which migrate to the large intestine. The trophozoites multiply by binary fission and produce cysts, and both stages are passed in the feces.
Because of the protection conferred by their cell walls, the cysts can survive days to weeks in the external environment and are responsible for transmission. Trophozoites passed in the stool are rapidly destroyed once outside the body and, if ingested, would not survive exposure to the gastric environment.
Hosts Humans are considered the main host for all of the discussed species except for Entamoeba polecki, which is usually associated with primates and swine. Geographic Distribution These amebae are found worldwide. Prevalence is highest in areas with inadequate sanitation. Clinical Presentation None of these amebae cause symptomatic disease in humans; colonization is noninvasive. However, the presence of trophozoites or cysts of nonpathogenic amebae in stool indicates that the person from whom the specimen was collected had fecal exposure.
Endolimax nana E. Mature cysts have four small nuclei with large, usually centrally located karyosomes and no peripheral chromatin. The nuclei are not visible in unstained wet mounts but are visible in iodine-stained wet mounts and slides stained with trichrome or iron hematoxylin i. The cytoplasm may contain diffuse glycogen but lacks chromatoid bodies. Figure A: Cyst of E.
Figure B: Cyst of E. Figure A: Cysts of E. Figure C: Cyst of E. Figure D: Cyst of E. The nucleus lacks peripheral chromatin. Their cytoplasm is granular and often highly vacuolated and may contain inclusions of bacteria. Trophozoites of E. Figure A: Trophozoite of E. Figure B: Trophozoites of E. Figure C: Trophozoite of E. Figure D: Trophozoite of E. Entamoeba coli E. Mature cysts typically have 8 nuclei but may have as many as 16 or more.
Entamoeba coli is the only Entamoeba species found in humans that has more than four nuclei in the cyst stage. The nuclei may be seen in unstained as well as stained specimens. Karyosomes may be compact or diffuse and are usually eccentrically located.
Peripheral chromatin is present and is often coarse, granular, and irregularly arranged along the nuclear membrane but may be more uniform. The cytoplasm of mature cysts may contain diffuse glycogen.
Chromatoid bodies are seen less frequently than in E. When present, they are usually splinter like with pointed ends, whereas the chromatoid bodies of E. Six nuclei are visible in this focal plane.
Five nuclei are visible in this focal plane. Seven nuclei are visible in this focal plane. Figure E: Cyst of E. Figure A: Immature cyst of E. Only two nuclei are visible; also notice the large glycogen vacuole.
Figure B: Mature cyst of E. Figure C: Mature cyst of E. In this specimen, at least five nuclei are visible in the shown focal plane. Figure D: Mature cyst of E. Figure E: Mature cyst of E. This figure and Figure F display the same cyst in two different focal planes, showing eight nuclei in total. Also, above the cyst in this figure, a trophozoite of Endolimax nana can be seen.
Figure F: Mature cyst of E. Eight nuclei can be seen between the two focal planes. The trophozoites have a single nucleus with a characteristically large, eccentric karyosome and coarse, irregular peripheral chromatin. Pseudopodia may be seen and are often short and blunt; movement in living trophozoites is nondirectional.
Figure B: Trophozoite of E. Figure C: Trophozoites of E. Entamoeba hartmanni E. Cysts of Entamoeba hartmanni are similar to those of E. Mature cysts contain four nuclei that have a small, discrete, centrally located karyosome and evenly distributed peripheral chromatin.
Cysts may not be visible in unstained specimens. The cytoplasm in mature cysts may contain diffuse glycogen and may have rounded or elongated chromatoid bodies with rounded ends.
Notice the chromatoid bodies, which have blunt ends. The trophozoites have a single nucleus that contains a small, compact, centrally or eccentrically located karyosome and fine, uniform peripheral chromatin. Nuclei are usually not visible in unstained specimens. The cytoplasm is finely granular. Movement in living trophozoites is described as nonprogressive.
Image courtesy of the Kansas Department of Health and Environment. In the upper-right quadrant of the image is a vacuolar form of Blastocystis species.
Figure E: Two trophozoites of E. Figure F: Trophozoite of E. Entamoeba polecki E. The nucleus is often large, measuring up to one-third of the diameter of the cyst.
The karyosome is pleomorphic in regards to size small to large , shape compact to diffuse , and location central to eccentric. Peripheral chromatin may range from light to heavy but is usually evenly distributed.
Cysts also contain an inclusion mass of variable size and numerous chromatoid bodies, which are highly variable in shape and size. Notice the numerous chromatoid bodies arrows.
Notice the large nucleus with a pleomorphic karyosome and numerous variably-shaped chromatoid bodies. Figure F: Cyst of E. The single nucleus is often distorted and irregularly shaped, with a small-to-minute centrally located karyosome. The peripheral chromatin is usually delicate and uniform. The cytoplasm is often vacuolated with a hyaline border. Blunt pseudopodia may be seen. Figure E: Trophozoite of E. Iodamoeba buetschlii Iodamoeba buetschlii cysts in concentrated wet mounts.
Cysts contain a single nucleus that is not visible in either unstained or iodine-stained wet mounts. With permanent stains such as trichrome , the nucleus contains a large, usually eccentrically located karyosome. Achromatic granules may or may not be present around the karyosome. An important diagnostic feature for this species is the presence of a large compact mass vacuole of glycogen in the cyst stage. Although this mass can be visible in unstained wet mounts, in iodine-stained preparations it takes on a darker, reddish-brown color.
The glycogen vacuole does not stain with trichrome but is visible as a well-defined mass. Figure A: Cyst of I. In this cyst, the glycogen vacuole can be seen as a large, oval refractile body. Figure B: Cyst of I. Figure C: Cyst of I. The glycogen vacuole is more easily observed as a dark-staining mass in the cyst.. Figure D: Cyst of I.
Iodamoeba bütschlii: características, morfología, ciclo biológico
Meztishicage High titers of serum antibodies also develop in patients with liver abscesses. Trichomonads are also characterized by flagella fg emerging from the anterior end. Trichomonas vaginalis does not reside within the iodamooeba tract, but is often discussed with the intestinal flagellates. Isoenzyme patterns are known for four amebic enzymes: A small intestinal biopsy, preferably from multiple duodenal and jejunal sites, may also reveal trophozoites attached to the intestinal epithelium.
Intestinal (Non-Pathogenic) Amebae