INFUSORIANS

From Big Medical Encyclopedia

INFUSORIANS (Infusoria, Ciliata) — a class of animals like protozoa. In total is apprx. 6000 types And., belonging to 5 subclasses: And. ravnoresnichny (Holotrichia), spiral and ciliary (Spirotrichia), krugoresnichny (Peritrichia), voronkoresnichny (Chonotrichia) and sucking (Suctoria). Apprx. 800 types And — parasites of various animals; And. a balantidiya (Balantidium coli) parasitize in a large intestine of the person, causing a heavy disease — balanthidiasis (see).

Fig. 1. Paramaecium caudatum: 1 — cilia; 2 — digestive vacuoles; 3 — a big kernel (macronucleus); 4 — a small kernel (micronucleus); 5 — an actinostome and a throat; 6 — the undigested remains of food which are thrown out outside; 7 — trikhotsist; 8 — a sokratitelny vacuole.
Fig. 2. The infusorian parasitizing in intestines of the person (Balantidium coli): and — an aktivnoplavayushchy form (1 — an actinostome; 2 — a kernel); — a cyst (1 — a kernel; 2 — a cover).
Fig. 3. An infusorian the trumpeter in the straightened state (Stentor coeruleus): 1 — a circumoral zone of the stuck together cilia (membranell); 2 — a sokratitelny vacuole; 3 — a micronucleus; 4 — a necklace-shaped macronucleus.
Fig. 4. The Bryukhoresnichny infusorian from the belly party (Styionichia mytilus): 1 and 6 — bodies of movement (1 — belly, 6 — tail); 2 — the stuck together cilia (membranella); 3 — the oral device with circumoral cilia; 4 — a micronucleus; 5 — a macronucleus; 7 — a digestive vacuole.

And. — the microscopic unicells possessing the complex structural organization of a body (fig. 1 — 4). The body surface is covered with a thin dense cover — a pellicle, under a cut in a layer of an ectoplasm the bases of cilia (basal grains, or kinetosomes), bodies of protection and attacks (trikhotsist), system of the basic and motive fibrilla connected through kinetosomes with cilia are located. Fibrilla takes part also in formation of an actinostome and a throat. Cilia at many types And. are located with the correct ranks; their movements are strictly synchronized and allow And. to move in any direction. In a layer of an endoplasm kernels, vacuoles, organellas of a general meaning (mitochondrions, secretory little bodies etc.) are located. Idiosyncrasy of all And. existence of kernels of two types — a macronucleus and a micronucleus is.

Food And. it is carried out by means of the cellular mouth (cytoostomy) conducting in a cellular throat (tsitofarinks), at the bottom a cut in cytoplasm digestive vacuoles form. The undigested remains of food are allocated through a proctal time (tsitopiga). At all fresh-water And. there are sokratitelny vacuoles performing osmoregulatory function. Breed And. division (asexual reproduction), Krom is usually preceded by sexual process. The rhythm of division and change of sexual and sexless processes of reproduction depend on a look And. and conditions of the environment. At approach of unfavorable conditions And. can form cysts.

Free living forms I. live in sea and sweet water. Presence of some of them at reservoirs serves as the indicator of extent of pollution of a reservoir.

Parasitic forms I. occur at different types of animals, most often in intestines (e.g., at ruminant in went. - kish. a path about 100 types are found And.). Some types And. parasitize on leather of fishes. So, And. ikhtioftirus, a trikhodina, hilodon and other types can cause mass death of juveniles of fishes.

And. use in laboratory practice for researches in the field of genetics, toxicology, pharmacology, radiology etc.

See also Protozoa , Protozoology .


Bibliography: Life of animals, under the editorship of L. A. Zenkevich, t. 1, page 134, M., 1968.

O. I. Chibisova.

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