''Endolimax'' is a genus of

amoebozoa Amoebozoa is a major taxonomic group containing about 2,400 described species of amoeboid protists, often possessing blunt, fingerlike, lobose pseudopods and tubular mitochondrial cristae. In traditional and currently no longer supported classi ...

that are found in the

intestine The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans ...

s of various animals, including the species ''E. nana'' found in humans. Originally thought to be non-pathogenic, studies suggest it can cause intermittent or chronic

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...

. Additionally, it is very significant in medicine because it can provide false positives for other tests, notably the similar species '' Entamoeba histolytica'', the

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

responsible for amoebic

dysentery Dysentery (UK pronunciation: , US: ), historically known as the bloody flux, is a type of gastroenteritis that results in bloody diarrhea. Other symptoms may include fever, abdominal pain, and a feeling of incomplete defecation. Complications ...

, and because its presence indicates the host has consumed fecal material. It forms

cysts A cyst is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble) ...

with four nuclei which excyst in the body and become trophozoites. ''Endolimax nana'' nuclei have a large endosome somewhat off-center and small amounts of visible chromatin or none at all.

Cyst

Cysts are small, with a spherical to ellipsoidal shape. Mature cysts contain four nuclei; immature cysts are rarely seen. These cysts measure 5–10 ''um'', with a usual range of 6–8 ''um''. In stained preparations, the nucleus has a distinct karyosome that, while not as large as that seen in the trophozoite, is still larger than the karyosome of the ''

Entamoeba ''Entamoeba'' is a genus of Amoebozoa found as internal parasites or commensals of animals. In 1875, Fedor Lösch described the first proven case of amoebic dysentery in St. Petersburg, Russia. He referred to the amoeba he observed microscopic ...

'' species. Peripheral

chromatin Chromatin is a complex of DNA and protein found in eukaryotic cells. The primary function is to package long DNA molecules into more compact, denser structures. This prevents the strands from becoming tangled and also plays important roles in r ...

is absent. Although the nuclei are not visible in unstained preparations, the karyosomes are readily apparent in

iodine Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a vi ...

-stained wet mounts. The

cytoplasm In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The ...

may contain diffuse

glycogen Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. The polysaccharide structure represents the main storage form of glucose in the body. Glycogen functions as one o ...

, and

chromatid A chromatid (Greek ''khrōmat-'' 'color' + ''-id'') is one half of a duplicated chromosome. Before replication, one chromosome is composed of one DNA molecule. In replication, the DNA molecule is copied, and the two molecules are known as chro ...

bodies are absent. Occasionally, small granules or inclusions may occur in the cytoplasm.

Trophozoite

This stage is small, measuring 6–12 ''

µm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

'', with an average range of 8–10 ''um''. Living trophozoites are sluggish and generally non-progressive. The single nucleus sometimes is visible in unstained preparations. In stained organisms, the karyosome usually is large and irregularly shaped, but occasionally it may be fragmented or placed against one side of the nuclear membrane. There is no peripheral chromatin on the nuclear membrane. The cytoplasm, which is coarsely granular and often highly vacuolated, may contain bacteria.Ash, Lawrence R. Atlas of Human Parasitology/Lawrence R. Ash, Thomas C. Orihel.-3rd ed.

References

Amoebozoa genera Conosa {{Amoebozoa-stub

Cyst

Trophozoite

See also

References