[Amoeboid properties of cells during early morphogenesis and the nature of a possible protozoan ancestor of Metazoa].

Data analysis reveals that cells of most of the metazoans (especially from the phyla Spongia, Placozoa and Cnidaria) at the early stages of morphogenesis demonstrateas amoeboid properties i.e. ability to form pseudopodia, to move by means of pseudopodia and to phagocyte.

[The basic types and forms of the fine structure of mitochondrial cristae: the degree of their evolutionary stability (capacity for morphological transformations)].

The organellological analysis being made of the fine structure of mitochondria in different species of the kingdom Protista, and in different cells of representatives of the kingdoms Plantae and Animalia (Metazoa). On the base of this analysis the following classification of types and forms of the fine structure of mitochondrial cristae is proposed. The Ist type, with lamellar (flat) cristae includes four morphological forms: ribbon, sheet, bundle-like and rounded ones (discoidal and plate-like).

[Eukaryotes devoid of the most important cellular organelles (flagella, Golgi apparatus, mitochondria) and the main task of organellology].

Comparative evidence on the lack of three important organelles (flagella, Golgi-complex, mitochondria) in cells and organisms at the cellular level of organization has been summarized for all the four eukaryotic kingdoms--Protista, Fungi, Plantae and Animalia (Metazoa). It is established that in the course of evolution these organelles may undergo the total reduction. There is no cellular organelle to be regarded as universal, indispensable.

[The origin of the eukaryotic cell. IV. The general hypothesis of the autogenous origin of eukaryotes].

The general hypothesis of autogenous (non-symbiotic) origin of the eukaryotic cell summarises some hypotheses explaining possible ways of the origin of main components and organelles of such a cell (the primary unicellular protist). Six hypothesises are suggested. Arising of the eukaryotic surface membrane of protist (cell) as a result of modification of its lipidoacidic composition, when most of synblocks and ensembles of eukaryotic enzymes sink into the cytoplasm (due to membrane vesiculation).

[The origin of the eukaryotic cell. III. Principles of the morphofunctional organization of the eukaryotic cell].

The eukaryotic plasmalemma, eukaryotic cytoplasm with its usual cytomembranes, and eukaryotic nucleus are obligatory components of the eukaryotic cell. All other structural elements (organelles) are only derivates of the aforesaid cell components and they may be absent sometimes. There are protozoans having simultaneously no flagelles, mitochondria and chloroplasts (all the representatives of phylum Microspora, amoeba Pelomyxa palustris, and others).

[The origin of the eukaryotic cell. II. A critical analysis of the symbiotic (exogenous) concept].

The exogenous (symbiotic) conception of the eukaryotic cell origin is unable to explain satisfactory the structure of mitochondria and chloroplasts. Either of these organelles possess its genome that can be compared with the viral one rather than with the bacterial one, judging by the dimensions and quantity of coding genes. The mitochondria resemble a little prokaryotes in the number of their proteins, chemical composition of their inner membrane and peculiarities of the protein-synthesizing apparatus.

[The origin of the eukaryotic cell. I. Historical sources and current state of the concept of symbiotic and autogenic origins of the cell].

The exogenous (symbiotic) conception of the eukaryotic origin is now widely spread. It is based on the recognition of the principle of combination (addition or enclosing) of diverse prokaryotic organisms; so the complicated unicellular eukaryotic organism (eukaryotic cell) was resulted. the principle of combination takes its historical scientific sources from the ideas of Buffon.

[Bacteria-cortical symbionts of Thichonympha turkestanica, a protozoan from the gut tract of the termite Hodotermes margabicus].

Intracellular symbiotic bacteria of the flagellate Trichonympha turkestanica located in the surface cortical part of the animal cell are described. The cell structure of the symbionts is typical of gramnegative bacteria, but contains also an additional outer membrane. The membrane is an element of the electron-dense structures which have contacts, at many points, with the kinetosomes or membranes surrounding flagella.