''Acroeimeria'' is a genus of parasites that contains those species which initially develop immediately beneath the brush-border of the intestinal epithelium, but the meronts and gamonts of which are early on extruded to form a layer on the surface of the gut mucosa. Morphologically they are similar to the ''

Eimeria ''Eimeria'' is a genus of apicomplexan parasites that includes various species capable of causing the disease coccidiosis in animals such as cattle, poultry and smaller ruminants including sheep and goats. ''Eimeria'' species are considered to be ...

'' to which they are closely related. The genus was described in 1989 by Paperna and Landsberg.

General features

The defining feature of this genus is their development, after becoming enclosed by extensions of the host cell membrane, within the resulting parasitophorous 'sack' which bulges out above the surface of the intestinal mucosa. This pattern of development is not known to occur in

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

s or

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

s but is common in

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

. The endogenous development of the parasite is intra-cytoplasmic, within the epithelial cells of the

ileum The ileum () is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine ma ...

. The parasites lie above (closer to the lumen) the host

cell nucleus The cell nucleus (pl. nuclei; from Latin or , meaning ''kernel'' or ''seed'') is a membrane-bound organelle found in eukaryotic cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, h ...

. Below the

parasitophorous vacuole The parasitophorous vacuole (PV) is a structure produced by apicomplexan parasites in the cells of its host. The PV allows the parasite to develop while protected from the phagolysosomes of the host cell. The PV is a bubble-like compartment mad ...

, the host cytoplasm expands as the volume of the parasite increases, giving rise to a short, stalk-like structure. The merozoite enters a gap formed in the host cell's brush border and then becomes enclosed by extensions of the host cell wall. A second, interior membrane is formed beneath the wall of the parasitophorous vacuole and this membrane is either confined to the proximal part of the parasitophorous vacuole or is ruptured distally. This membrane is retained throughout the growth and differentiation of the parasite.

Meront Apicomplexans, a group of intracellular parasites, have life cycle stages that allow them to survive the wide variety of environments they are exposed to during their complex life cycle. Each stage in the life cycle of an apicomplexan organism is ...

: These possess all the typical features of the Apicomplexia including an apical complex, sub-pellicular tubules and micronemes. Young meronts are bound by a single membrane, and contain large mitochondria and a few micronemes. Microgamont: Macrogamont: Young macrogamonts possess a large, vesicular nucleus with a conspicuous central

nucleolus The nucleolus (, plural: nucleoli ) is the largest structure in the nucleus of eukaryotic cells. It is best known as the site of ribosome biogenesis, which is the synthesis of ribosomes. The nucleolus also participates in the formation of sig ...

. The cytoplasm contains a bilobed medium-density granular inclusion. The cytoplasm is densely packed with ribosomes and has a dense endoplasmic reticulum. The nucleus of The parasite is fringed by numerous adnuclear bodies. In the late stages of maturation, the cytoplasm becomes filled with

amylopectin Amylopectin is a water-insoluble polysaccharide and highly branched polymer of α-glucose units found in plants. It is one of the two components of starch, the other being amylose. Plants store starch within specialized organelles called amylopl ...

granules. The macrogamonts are bound by a single unit membrane, coated by a variable amount of glycocalyx.

Oocyte An oocyte (, ), oöcyte, or ovocyte is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female ...

: The oocysts possess four sporocysts each containing two

sporozoite Apicomplexans, a group of intracellular parasites, have life cycle stages that allow them to survive the wide variety of environments they are exposed to during their complex life cycle. Each stage in the life cycle of an apicomplexan organism i ...

s. Like most of the ''Eimeria'' species infecting reptiles the sporocysts of these species lack both Stieda bodies and substieda bodies.

Host-parasite relations

* ''Acroeimeria cnemidophori'' — teiid lizard ('' Cnemidophorus lemniscatus lemniscatus'') * ''Acroeimeria paraensis'' — teiid lizard ('' Cnemidophorus lemniscatus lemniscatus'') * ''Acroeimeria pintoi'' — teiid lizard (''

Ameiva ameiva ''Ameiva ameiva'', also known as the giant ameiva, green ameiva, South American ground lizard, or Amazon racerunner, is a species of lizard in the family Teiidae found in Central, South America, and some Caribbean Islands. Geographic range It ...

'') * ''Acroeimeria rouxi'' — marble-throated skink ('' Marmorosphax tricolor'')

References

{{Taxonbar, from=Q4675768 Apicomplexa genera