The simplest (Protozoa) - type single-celled animals, which includes more than 25 thousand species. Most simplest lead a free life, dwelling in seas and oceans (in the water column and on the seabed), as well as in fresh water and in the soil. More than 6700 species of protozoa are parasites of humans, animals and plants. Some of them causes serious diseases - malaria (see), amoebiasis (see), trichomoniasis (see), leishmaniasis (see), toxoplasmosis (see), giardiasis (see), balantidia (see), pneumocystosis (see) and others, and the animals - piroplasmosis, beasiality, coccidioses, trichomoniasis, toxoplasmosis, Trypanosomosis and other
The sizes of the simplest more often from 2 to 50 MK. The simplest form of the body varies greatly. The body of the simplest consists of cytoplasm, nucleus and organelles. Some protozoa have an outer skeleton in the form of shell or shell, and other basic features an internal skeleton consisting of various forms of silicon needles or fibrils. The simplest is both the cell and independent body, which is peculiar to all vital functions: metabolism, irritation, movement, reproduction , etc.
Life cycles of simple varied and sometimes reach a high degree of complexity (see Malaria). Some simple form a resting stage. Multiply the simplest asexual (division into 2 or more cells) or sexually. Sexual reproduction can be accompanied by a change of owners.
Methods of study of the simplest diverse - used native preparations, methods of enrichment, prepared from the simplest culture. For the diagnosis of diseases caused by pathogenic protozoa (toxoplasmosis, malaria, amebiasis and other), used serological and Allergy research methods, widely used achievements in the field of Cytology, histology, electron microscopy, biochemistry and other

The simplest (Protozoa) - type single-celled mostly microscopic animals. The simplest cannot be likened to a cell of a multicellular organism, because every P. a whole organism, not a specialized part of it. There are about 25 000 species P.; of them 6710 - parasitic forms. Other protozoa - free-living - inhabitants of the oceans, seas, lakes, freshwater and salt water, soil and wet sand.
The sizes of the simplest range from 2 to 50 microns and more. The shape of their body is diverse. Many representatives of flagellar and some of the ciliates body elongate; radiolarians, Solnechnyi, sporewiki often have spherical the form, amoebae and some other simple and irregular forms. Body P. consists of an outer casing, cytoplasm, nucleus and organelles. Most of P. in the cytoplasm can be distinguished: the outer layer - homogeneous - ectoplasm and the inner part, more liquid - endoplasm; in it are usually the core, vacuole and a large number of inclusions. Ectoplasm in different representatives P. constructed differently. With many it is very complex structure. On the surface of a body of ciliates are cilia, the representatives of the class flagellate - harnesses, which are organelles movement. The flagellar has one or more kinetic (blepharoplasty + basal body). From them, there is a flagellum (one, several, or many). The ciliates basal bullock are located in the surface layer of protoplasm, they are moving away cilia. On a body surface (or near it) at some of the simplest is a complex network of fibrils; their function reference, sometimes contractile. The supporting elements P. often varied and complex in structure and purpose. A number of P. available external skeleton in the form of shells (for example, marine and freshwater corneous) or in the form of a shell (some flagellar).
The core of the simplest similar to the nuclei of the cells of other animals (see the Cell, the nucleus of the cell). In most cases with P. one core, but the ciliates their two - macro - and micronucleus. Some of the simplest multiple cores. The kernel can be puzirkoviy (amoebae and many other Petrograd) and massive (micronucleus infusoria). Nuclear fission is not the same in different simplest, most commonly observed mitosis, rarely amicos. The development cycle of the simplest very diverse. For many simple characterized by a complex life cycle, such as the malaria parasites.
The simplest systematics is based on the methods of movement, morph, features and development cycles. The simplest type is divided into five classes: sarkodie (Rhizopoda), flagellates (Mastigophora), sporewiki (Sporozoa), Cladosporium (Cnidosporidia), infusoria (Infusoria). Sarkodie include a large number of free-living of the inhabitants of the seas, oceans, freshwater bodies. Some of them - representatives of the genera Entamoeba, Endolimax, Jodamoeba, Hartmanella and others are parasites of humans and animals. Flagellar include a lot of free-living of the inhabitants of various reservoirs. Many of them are parasites of animals and humans (see Amebiasis, Leishmaniasis, Giardiasis, Trypanosomosis, Trichomoniasis, Toxoplasmosis). Sporewiki - all parasites of animals and humans. Typical representatives of coccidia (see Coccidiosis), causing malaria (see), cercopoidea (see Sarcoptoides) and agents of pneumocystosis (see). Cladosporium - parasitic protozoa living mainly in fish (Myxosporidia) and arthropods (mostly insects), rarely in vertebrates (Microsporidia). Ciliates, or ciliary,in most free living. Among parasites person important Balantidium coli (see Balantidia).
Methods of study of simple varied. To study the simplest human intestinal use native preparations, methods of enrichment, prepared from P. culture, infect susceptible animals, and others To explore P., parasites in the blood and tissues, use methods used in the study of blood, and the method of cultivation of protozoa in different environments, tissue culture and assay on animals. For the study of diseases caused by pathogenic protozoa, which are not perebivaetsya in laboratory animals and is not cultivated at the environments and tissue cultures, applied methods of study on models. So, some questions malaria person decide, infecting the malaria parasites of birds, including chickens, Redpolls, Siskins, Canaries. For the diagnosis of diseases caused by pathogenic protozoa (toxoplasmosis, malaria and other), used serological methods (RSK, haemagglutination reaction, the reaction of IgM antibodies and other), and allergic - intradermal test, for example with toxoplasmosis. Widely used for these purposes and methods of Cytology, histology, electron microscopy, biochemistry, and other microcinematography