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M N Gruzova

Publications and source records attributed to M N Gruzova.

At least 19 recordsLinked to original sources
PubMed1995

[The formation of the karyosphere in the oogenesis of insects and amphibians].

This review deals with the authors' own and literary data on the ultrastructural and cytochemical organization of insect and amphibian oocyte nuclei, with special attention being paid to the karyosphere and its capsule. The evidence provided is supplemented with data on isolated karyospheres in Rana temporaria oocytes. A conclusion is made that the karyosphere is a complex structure which contains all chromosomes in the limited space of the oocyte nucleus, and that these chromosomes are, as a rule, in the process of inactivation. It is inferred that the karyosphere capsule commonly appears in gigantic oocyte nuclei (more than 100 micron in diameter) containing extrachromosomal DNA. The analogy of capsule organization in different invertebrate and vertebrate species is discussed, in addition to the involvement of presumably homologous nuclear structures (e.g. derivatives of synaptonemal complexes and nuclear envelope) in capsule formation. It is assumed that the karyosphere capsule is a specially organized part of the nuclear matrix. The capsule provides nuclear compartmentalization and chromosome localization in the germinal vesicle. Studies of this sort open up new possibilities to further investigation of intranuclear morphogenesis.

Amphibians↗
PubMed1986

[Nucleoli and nucleolus-like bodies in oogenesis stained by silver nitrate].

The nuclear structures were studied in oocytes of two frog species (Rana temporaria and R. ridibunda) in oocytes and trophocytes of three insect species (Blaps lethifera, Laspeyresia pomonella and Chrysopa perla) by the AgNO3-staining method (Howell, Black, 1980). The previously investigated nucleoli of the insect trophocytes and the extra-r-DNA bodies of Chrysopa oocytes were used as test objects. It is demonstrated that in oogenesis, contrary to somatic cells, AgNO3 impregnates both transcriptionally active nucleoli and inactive nuclear structures: extra-r-DNA bodies, nucleolus-like bodies (NLB) and some microbodies. The relationship of Ag+ NLB and microbodies to nucleolar structures is discussed in addition to the role of the r-DNA compactness for the Ag+ reaction.

Animals↗
PubMed1985

[Intranuclear lipids in the late oocytes of the common frog].

The complex of chromosomes and nucleoli, constituting the karyosphere with a capsule, was removed micro-surgically from the late oocyte nuclei of Rana temporaria. Lipids of nuclei and of karyosphere were investigated using biochemical and autoradiographical methods in hormone-stimulated maturing oocytes in vitro. Neutral lipids (triglyceride, diglyceride, cholesterol ester) were found in the karyosphere substance by thin-layer chromatography. During oocyte maturation the incorporation of a precursor (3H-glycerol) into triglyceride was seen to increase much more than into lecithin. The autoradiography on the sectioned oocytes showed that the intranuclear level of 3H-glycerol was more densely distributed in the nucleolar zone over the material of a fibrous component of the karyosphere capsule. The level was also detected over the central part of the karyosphere in close proximity to the chromosomes. The involvement of lipids in organization of the complicated intranuclear complex of the karyosphere with a capsule is discussed. It is suggested that lipid accumulation in the area of the karyosphere fibrous component may reflect their functional relation with the oocyte nuclear matrix.

Animals↗
PubMed1984

[Nuclear ultrastructure of the oocytes from human antral follicles. Formation of the karyosphere].

The organization of the nucleus in the oocytes from human antral follicles was examined at the electron microscopic level. At this time all the chromosomes are aggregated around an inactivated nucleolus forming a karyosphere 5-7 micron in diameter. The nucleolus bears no granular component and consists of densely packed delicate fibrillar material. The peripheral zone resembling a ring 0.5 micron thick is separated in the nucleolus. Nucleolus-like bodies (NLB), consisting of granules 20 nm in diameter embedded in finely fibrillar material, are constantly observed in contact with the chromatin. The eventually formed karyosphere is a complex of intimately interconnecting structures--the nucleolus, chromosomes and NLB. However, the chromatin surrounding the nucleolus does not form a continuous (compact) mass as it is observed at the light microscopic level. It is determined that the human karyosphere is formed during the preovulatory period when the connection between oocyte and follicular cells of cumulus oophorus is lost. The duration of karyosphere existence in the human oocytes, and relation of the karyosphere to the processes of antral follicle atresia are discussed.

Adult↗
PubMed1984

[Characteristics of karyosphere formation in the lake frog. Electron microscopic data].

The ultrastructural organization of the karyosphere in oocytes of R. ridibunda during formation of its central body (CB) was examined. It is shown that the material of CB consisting of pores similar to those of the nuclear envelope makes some intimate contact with DNA-containing fibrillar micronucleoli (MN). In the zone of this contact a transfer of MN fibrils into CB is observed. The electron microscope data on the nucleolar origin of numerous MN are provided. It is suggested that MN supply the material for the formation of CB. The participation of r-DNA in this process is discussed.

Animals↗
PubMed1983

[Characteristics of karyosphere formation in the lake frog. Light microscopy data].

Morphological peculiarities of the oocyte nuclear organization were examined in R. ridibunda during winter and spring (February-March). Numerous nucleoli were seen to be assembled around regressive lampbrush chromosomes in the centre of the nucleus, and a central body was formed to which the chromosomes were attached. As result, a structural complex is constituted that involves a karyosphere and a capsule. Nucleoli are characterized by segregation and intensive fragmentation of their material. In result, a considerable part of nucleolar DNA is eliminated in the form of ring and polymorphous structures (micronucleoli). Besides the membranous component of nucleoli (nucleolar threads or tails) is lost. Towards the end of this period, nucleoli with complicated morphology become spherical again. The formation of the central body is started from the appearance of some small optically-light protein structures 5-20 nm in diameter (central body precursors-CBP). CBP are closely surrounded with ring micronucleoli to make intimate contact with the chromosomes and nucleolar threads. CBP commonly lie in one region of the nucleus not far from each other. The formation of a definitive central body obviously occurs due to a fusion of some small CBP. A conclusion is made of the nucleolar origin of the ring and polymorphous structures and of their essential role in the central body formation. The participation of chromosomal and eliminated nucleolar DNA in this process is discussed.

Animals↗
PubMed1982

[Nuclear organization of the oocytes from atretic follicles of the lake frog].

Oocytes of Rana ridibunda were examined by light and electron microscopy. A peculiarity of these oocytes is the availability of the vast local growings of the inner nuclear membrane, their expansion into the nucleus and the formation of cluster accumulations of membrane structures - intranuclear vesicles filled with fibrillar protein material. In the regions of nuclear membrane expansion some disturbances in the nuclear envelope are noted: disappearance of nuclear pores, replacement of membranes by filamentous material, and formation of nuclear membrane gaps. It is suggested that growings of the inner nuclear membrane are related to the isolation of cytoplasmic proteins penetrating into the nucleus. A general pattern of the karyospheric structure, characteristic of the normal developing oocytes, remains unchanged during degeneration as well. The karyosphere is a complex consisting of the central protein body (CPB), chromosomes associated with this body and numerous nucleoli surrounding the chromosomes. Some differences in details of the structure of karyosphere in the examined oocytes are revealed. Thus, the CPB in these oocytes consists of pseudomembranes, but autonomous pore complexes here occur seldom. The chromosomes have a tendency to fuse forming in some cases a unique network of the chromatin material associated with the material of CPB. In the contact zone the transfer of chromatin fibrils into pseudomembranes is observed. The nucleoli bear no granules and demonstrate a segregation of the fibrillar material. As the result, DNA-containing material of the fibrillar centre appears at the periphery of nucleoli. Analysis of our own and literature evidence on the morphology of the oocyte nuclei from the atretic follicles of different vertebrates, and on the structure of ciliate micronuclei degenerating during conjugation allows a conclusion on the identical response of sexual cells to different stimuli evoking degeneration.

Animals↗
PubMed1979

[Nuclear structures in the telotrophic ovarioles of nocturnal ground beetles (Tenebrionidae, Polyphaga). II. The oocyte nucleus of Blaps lethifera and Gnaptor spinimanus. Light optical data].

Changes in the nuclear structures and their participation in RNA synthesis in the growing oocytes were followed in two species of beetles Blaps lethifera and Gnaptor spinimanus. In the oocytes of both the species, the chromosomes join into the karyosphere following the short-term lampbrush stage. A large capsule appears around the karayosphere which consists of the fibrous substance, granules and karyosphere nucleoli. The latter form in the karyosphere and contain RNP but they are not true nucleoli since they do not include 3H-uridine. RNA synthesis on the chromosomes, active at the lampbrush stage, falls markedly following their joining into the karyosphere. The oocyte nuclei of these beetles are, thus, characterized by the absence of RNA synthesizing nucleolar system and, as compared with the trophocytes, by the low level of RNA synthesis on the chromosomes.

Animals↗
PubMed1979

[Nuclear structures in the telotrophic ovarioles of nocturnal ground beetles (Tenebrionidae, Polyphaga). III. The oocyte nucleus. Electron microscopic data].

The fine structural organization of nuclei was studied in the growing oocytes of Blaps lethifera, B. mortisaga and Gnaptor spinimanus. In the beginning of diplotene the nuclei contain primary fibrillar nucleoli and numerous electron dense globules dispersed all over the nucleus; the loose chromosome material (lampbrush chromosomes) is distributed all over the nucleus. With the oocyte growth the chromosomes are spiralized and join into the karyosphere. A capsule of fibrous material forms around the karyosphere. The karyosphere nucleoli appear on the chromosomes and, then, move to the capsule region and outside its limits, to the nuclear envelope. They are fibrillar and non-active with respect to RNA synthesis. The fibrous material of the capsule is represented by strands which consist of bundles of cross-striated filaments. These latter contact directly with the chromosomes in the karyosphere and with the surface of the karyosphere nucleoli. The fibrillar-granular bodies are distributed along the strands in the capsule; they contain both RNA and DNA. The nature of extrachromosomal DNA in the karyosphere capsule and its participation in the formation of the capsule material are discussed. A suggestion is put forward on the similarity of the capsule strands with the modified central elements of synaptinemal complex.

Animals↗
PubMed1976

[Nuclear structures in the late oogenesis of Rana temporaria. III. Electron microscopic studies].

The ultrastructural organization of the vitellogenic oocyte nucleus (stage VI, according to Duryee, 1950) was studied in normal and in vitro hormone-stimulated maturing oocytes of Rana temporaria. At this stage, numerous nucleoli are gathered around the knot of highly contracted chromosomes (the karyosphere) thus making the karyosphere capsule. Light microscope observations reveal three zones in the capsule: a central fibrous zone separating the chromosomes from the nucleoli, a middle zone, consisting of numerous nucleoli and a distinct fibrous componen; in addition a fibrous zone on the capsule periphery is seen. The nucleoli are fibrillar, bear no proribosomal granules and do not synthesize RNA. This period is characterized by an intensive fragmentation and segregation of the nucleolar material. Numerous micronucleoli and nuclear bodies occur in the nucleus. The nucleoli are normally compound and irregular in shape to become spherical in hormone-stimulated maturing oocytes. In the central fibrous zone of the capsule, separating the chromosomes from the nucleoli, some peculiar abundant accumulations of annuli were detected lacking the membranes component. Annuli are linked with the fibrous material and are regularily packed making peculiar pseudomembranes (PMM). The chromatin is connected with PMM directly. In the middle zone of the capsule, accumulations of PMM are also seen, though less abundant and less regularly packed; along with annuli, membranous areas of various size and form are met in PMM. PMM are connected with the micronucleoli with filaments 20 nm thick. In the peripheral zone of the capsule, a variety of membranous structures is detected: intranuclear annuli lamellae, component of the capsule consists of different membranous and pseudomembranous (with annuli) structures. A question of the contribution of the chromatin material in the formation of the fibrous capsular component (PMM and membranous structures) is discussed.

Animals↗
PubMed1975

[Nuclear structures in the late oogenesis of the common frog. I. Light microscopic observations].

The dynamics of the Rana temporaria karyosphere formation throughout different seasons was studied in addition to morphological changes in the karyosphere components with and without hormonal stimulation of oocyte maturation in vitro. Towards the end of summer, the nuclear structure (lampbrush chromosomes and multiple nucleoli) were shown to assemble in the centre of the nucleus forming a karyosphere. The completely formed karyosphere (up to 150--200 mu in diameter) is observed during autumn and winter to consist of the central chromosome part and a surrounding capsule. The capsule consists of numerous nucleoli and a distinct fibrous component. Filaments penetrating the whole nucleolar zone of the capsule are tightly packed around the chromosomes, thus forming the inner fibrous zone of the capsule, separating the chromosomes from the nucleoli. On the periphery of the karyosphere, threads attached to the nucleoli are clearly seen. This pattern of the karyosphere construction is conserved through winter till spring. In winter, spherical nucleoli change into rings and necklaces. In spring, nucleoli become spherical again and lose their threads. In the period of oocyte maturation and disappearance of nuclear envelopes, numerous nucleoli fuse into a single conglomeration which later disappears. Only the inner fibrous zone is conserved which separates the chromosomes from the cytoplasm and yolk platelets. In this state, the karyosphere persists up to the first meiotic metaphase. The nature of the fibrous component of the karyosphere capsule, its origin and function are discussed.

Animals↗
PubMed1975

[Nuclear structures at late stages of Rana temporaria oogenesis. II. Autoradiographic data].

Seasonal dynamics of RNA synthesis in the nuclei of 3rd year vitellogenetic oocytes of Rana temporaria has been studied by autoradiography. The nucleoli and chromosomes exhibit the highest level of RNA synthesis in summer, when lampbrush chromosomes are well developed, and multiple nucleoli start moving away from the nuclear membrane. The weakening of RNA synthesis is observed in autumn, when the nuclear structures assemble in the centre of the nucleus to form the karyosphere. The synthesis level is the lowest in winter, and increases in spring. The karyosphere of Rana temporaria is involved in protein metabolism of oocytes. Possible reasons of the seasonal RNA synthesis dynamics by the oocyte nuclei are discussed.

Animals↗
PubMed1975

[Differentiation of oocytes and trophocytes in insect ovaries with different ovariole structures].

Early stages of differentiation of the oocytes and nurse cells are comparatively studied in the polytrophic ovarioles in larvae, pupae and imago of the butterfly Laspeyresia pomonella and in the telotrophic ovarioles in larvae and imago of the bug Eurigaster integriceps. In L. pomonella, the oocytes and trophocytes, being the descendants of one oogonial cell, pass synchroniously through early stages of meiotic prophase up to the pachyten. After the pachyten chromosomes of the future trophocytes transform into diakinetic bivalents, whereas in the oocyte nucleus chromosomes retain their pachyten stage appearance. In the fifth instar larva of E. integriceps, two zones may be seen in the germarium of the telotrophic ovariole: the apical trophocyte zone and the distal oocyte zone. The oocytes develop up to the zygotene("bouquet") stage. As to the future trophocytes, they miss zygotene and reach directly diakinesis. Thus,the earlier divergence in the development ways of oocytes and trophocytes is observed in the telotrophic ovarioles, since the trophocyeres pass themeiotic stages more quickly then oocytes. The supposition is advanced that the quicker development of the nurse cells in the bug's ovarioles takes place due to missing the synaptonemal complex formation. The patterns of similarity and distinction between the telotrophic ovarioles in Coleoptera, on the one hand, and the polytrophic ovarioles of the butterfly L. pomonella and telotrophic ovarioles of the bug E. integricept, on the other hand, are discussed.

Animals↗
PubMed1975

[Ultrastructure of trophocyte nuclei in polytrophic ovarioles of Chrysopa perla (Neuroptera)].

The light and electron microscope and autoradiographic studies (H3-uridin incorporation) were carried out on the trophocyte nuclei of imago polytrophic ovarioles of Chrysopa perla (Neuroptera), from the trophocyte differentiation up to their degeneration. Like the oocytes, one of the seven nurse cells o every ovariole chamber contains extrachromosomal DNA bodies. This nurse cell is formed during differential mitoses in the germarium as one of two prooocytes. In contrast to extrachromosomal DNA of oocytes the trophocyte DNA bodies are less active structures. Several (2--4) complex nucleoli develop in the trophocytes of Chrysopa in the early stages of oogenesis. They consist of three main components: the chromatin mass, fibrillar bodies and granular strands. Such nucleoli grow, through increasing in number of fibrillar bodies and granular strands. They are most developed by the start of the vitellogenesis. At the middle vitellogenesis the general nucleolar structure modify due to the beginning of trophocyte degeneration. The consecutive stages of nuclear degeneration are described. The trophocyte nucleoli synthesize RNA still in germarium. The most intensive RNA synthesis is observed at the beginning of the vitellogenesis to decrease by the beginning of trophocyte degeneration.

Animals↗
PubMed1975

[Karyosphere in oogenesis].

The purpose of this review is to draw attention to the peculiar phenomenon during gametogenesis: the formation of the karyosphere. This phenomenon is characterized by concentration of all chromosomes in the limited area of the nucleus and may be considered as alternative of the genome in the state of lumpbrush chromosomes. The formation of the karyosphere is a widely spread phenomenon during oogenesis of different animal classes. The karyosphere can be developed during different stages of oogenesis in different organisms; but as a rule the chromosomes of diploten stage of meiosis take part in its formation. As to functional identity of the karyosphere in different species, special investigations are to be done, but contemporary knowledge of the karyosphere formation reveals some common feature:1) in the karyosphere the chromosomes are in a relatively spiral state as demonstrated by the positive Feulgen reaction; 2) there is a low level of RNA synthesis or the absence of it in the karyosphere; 3) during the karyosphere formation the nucleus is enriched by the acid proteins and a lot of protein granules and structures appearing in a close contact with the karysphere. The more typical examples of the karyosphere formation can be observed in the insect oocytes belonging to the nutrimentary type of oogenesis. In the oocytes of some animals the peculiar protein substances are formed around the chromosome knot and appear as a fibrillar zone. Such karyosphere appears to be a kind of capsule inside the nucleus. The capsules are developed as a result of complex interaction between the main nuclear structures; chromosomes, nucleoli, and nuclear membrane as it is manifested by the analysis of some recent ultrastructural date obtained in some insect and amphibian oocytes. The function of the karyosphere capsule and the role of the nuclear structure (sinaptonemal complex, extrachromosomal DNA, and nuclear membrane) in formation of the capsule, are discussed as well as the ultrastructural and cytochemical similarity between the karyosphere capsule of oocytes and nuclear bodies of somatic cells.

Amphibians↗