FLAGELLATES

From Big Medical Encyclopedia

FLAGELLATES (Mastigophora Diesing, 1865; synonym Flagellata) — the class like elementary (Protozoa) combining unicells which characteristic sign is existence of a threadlike outgrowth on a body — a plait (flagellum) performing functions of organoid of the movement; one types. — free living forms, others lead a parasitic life.

The St. 5500 types are described., from which apprx. 1400 — parasites of the person, animals and plants. The class Mastigophora includes three subclasses. Representatives of a subclass of Phytomastigina — autotrophic organisms (see); being inhabitants of fresh-water reservoirs and the seas, they play an important role in biocenoses. a subclass of Zoomastigina — heterotrophic organisms (see). Also representatives of a subclass of Opalinina who were carried to infusorians earlier have the same type of food. The last parasitize in intestines of amphibians, have numerous kernels, their body is covered with the shortened plaits reminding cilia of infusorians. The main component of a plait — the bunch of ultrathin tubules (2 central and 9 steam rooms peripheral) dressed by the cover representing continuation of a cytoplasmic membrane. Majority. has not one, and several plaits which set forms the motive device. At some types (a trypanosome and a trichomonad) the plait adjoins to a body, connecting to it a thin membrane — an undulating membrane.

Morphologically. represent a cell with one or several kernels, the motive device, cytoplasmatic organoids and a complex of the microfibrils bearing basic functions. Body of some free living. it is put into the firm cover consisting of mineral or organic substances.

Life cycle. it consists of generations of the individuals breeding binary fission: at first the kernel and plaits, and then cytoplasm share. At a part of types a life cycle includes sexual process as copulation. Originality of life cycles parasitic. consists available certain stages or alternation of the generation providing circulation of a parasite. So, majority. — parasites of intestines forms the based stages — the cysts worrying in external environment until hit in the new owner. At leyshmaniye and trypanosomes a life cycle consists of generation of morphologically differing individuals breeding in an organism of a carrier and the owner.

Some representatives of flagellates: I \Chilomastix mesnili mesnili — a nonpathogenic parasite of a large intestine of the person (full size of 6 — 18 microns); II \stages of a life cycle of representatives from the Trypanosomatidae family — pathogenic parasites of blood of vertebrata and the person: and — an amastigotny form; — a promastigotny form; in — an epimastigotny form; — a tripomastigotny form; 1 — a kernel; 2 — kinetoplast; 3 — a plait; 4 — an undulating membrane; III \Trichomonas fetus foetus — a parasite of a genital tract of cattle (full size of 10 — 25 microns); IV \Trichomonas vaginalis — — the activator of an urinogenital trichomoniasis of the person (full size of 10-— 25 microns); V \Trichomonas hominis hominis — a parasite of a large intestine of the person (full size of 5 — 15 microns); VI \Lamblia Lamblia intestinalis — a parasite of a small intestine of the person (full size of 10 — 18-microns); VII \Trichonympha turkestanika — — a parasite of termites (full size of 150 — 170 microns).

From the medical point of view the subclass of Zoomastigina is of the utmost importance, many representatives to-rogo parasitize at the person. This group is divided into 6 groups. The Choanoflagellida group combines the free living flagellates having the only plait concluded in a funneled outgrowth of a body (collar). Belong to Protomonadida group. with rather just arranged motive device including from 1 to 4 plaits. Many parasitic organisms belong to Protomonadida group. So, nonpathogenic Chilomastix mesnili (fig., 1), Embadomonas intestinalis and Enteromonas hominis live in a large intestine of the person.

A characteristic sign of Kinetoplastida group — organoid, adjacent to a kinetosome — kinetoplast (see. Taurus basal ). The most part of types of group belongs to the Trypanosomatidae family, representatives to-rogo have the only plait. Change of forms is characteristic of their life cycle (fig., II). All types of this family — parasites. Representatives of the sorts Leishmania and Trypanosoma parasitize in blood and tissues of vertebrata and are transmitted through arthropod. Special value have L. tropica, L. donovani and L. brasiliensis which are activators leyshmanioz (see), and T. cruzi, T. gambiense and T. rhodesiense — activators trypanosomiasis (see).

The group of trichomonads belongs to Polymastigida group, to-ruyu many protozoologists allocate in independent group Trichomonadida; many of them pathogens. So, Hystomonas meleagridis and Trichomonas gallinae cause diseases in birds, Trichomonas fetus (fig., III) affects a genital tract of cattle, a Trichomonas vaginalis (fig., IV) is the activator of an urinogenital trichomoniasis of the person. At the person two more look, nonpathogenic for it, parasitize: Trichomonas hominis — in intestines (fig., V) and Trichomonas elongata — in an oral cavity.

The Hypermastigida group is evolutionarily close to trichomonads. His representative — Trichonympha turkestanika (fig., VII) has numerous sets of plaits and parabasal bodies. These. live in intestines of termites and some cockroaches and bring benefit to the owners, providing digestion of cellulose.

Representatives of Diplomonadida group have a bilateral and symmetric body, two kernels and the doubled set of plaits — 4 couples at the majority of types. The group is presented by free living and parasitic types. At the person in a small intestine Lamblia intestinalis (fig., VI) which is especially often meeting at children parasitizes. Data on a role of it. in pathology of the person are contradictory.

Fight with. — causative agents of diseases of the person includes treatment of the patient with specific drugs (see. Trichomoniasis , Lambliasis , Leyshmanioza , Trypanosomiasis ), and also the actions directed to the prevention of spread of an infection. In case of infection., not having carriers (the lyambliya, trichomonads), needs first of all strict observance of rules of personal hygiene. At the leyshmanioza and a trypanosomiasis which are transmitted by blood-sicking insects, actions shall be directed to destruction of a carrier, prevention of its attack on the person, to destruction of natural owners of a parasite (big sandworts — at a skin leushmaniosis of rural type).


Bibliography: Dogel V. A., Polyansky Yu. I. and Heysin E. M. The general protozoology, M. — L., 1962, bibliogr.; The multivolume guide to microbiology, clinic and epidemiology of infectious diseases, under the editorship of H. N. Zhukova-Verezhnikov, t. 9, M., 1968; The Guide to cytology, under the editorship of A. S. Troshina, t. 1, page 409, M. — L., 1965.

M. M. Solovyov.

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