PubMed Health⌕ Search

Biomedical subjects

T V Davydova

Publications and source records attributed to T V Davydova.

At least 55 records · Page 3Linked to original sources
PubMed1983

Phylogenetic and ecological features of the structural organization of the forebrain cortical plate in Chelonia: 1. Neuronal composition and dendrite spines of the cortical zones in land and aquatic Chelonia.

A comparative study was made of cytoarchitectonics, neuronal composition and ultrastructural organization of the three basic cortical zones (hippocampal, dorsal and pyriform) of the forebrain of four members of Chelonia (two aquatic and two land species). The features under study fall into three major groups as follows: (1) common to all the Chelonia under investigation and possibly of the entire order; (2) ecologically specific, i.e. common to animals with similar ecology and different in animals with different ecology; (3) species-specific, i.e. differing in individual species. The common structural features of the forebrain cortical plate in Chelonia underlie the morphological substrate responsible for specific functions in different cortical zones. It is precisely with respect to the common features that the dorsomedial dorsal cortex exhibits a more complex neuronal and synaptic organization as compared with other cortical zones. This part of Chelonia cortex is assumed to be homologous to mammalian neocortex. The more plastic ecologically specific and species specific features appear to provide adaptive specializations within a particular level of the nervous system organization.

Animals↗
PubMed1983

Phylogenetic and ecological properties of the structural organization of the cortical plate in the forebrain of Chelonia. 2. Axo-spinal synaptic complexes of the plexiform layer of the cortical zones in aquatic and land Chelonia.

An ultrastructural study is performed with a quantitative analysis of some parameters of the synaptic organization of the superficial plexiform layer of the three basic cortical zones (hippocampal, dorsal and pyriform) of the forebrain in two aquatic and two land Chelonia species. On the basis of our own and literature data it is inferred that all the basic elements of the axo-spino synaptic complexes (dendritic spines--active synaptic zones--nerve endings) exhibit both stability, ensuring the structural durability and reliability of the contacts' functioning, on the one hand, and plasticity responsible for homeostasis and adequate transformations, on the other. Normally, functional shifts in the fine structure of synaptic apparatus are presumably too slight to conceal the specific features of the nerve centres' synaptic organization. This made feasible a comparative study of the structure of the axo-spinal complexes in functionally dissimilar zones, which revealed the following three categories of characters: (1) stable, common of all the Chelonia species under study and characterizing a particular level of the integration of nervous processes, and (2) variable, ecologically-specific and (3) species-specific, ensuring adaptation changes within a given level of interneuronal organization. It has been revealed that ecological differences in the synaptic organization of the cortical zones in the aquatic and land Chelonia are most pronounced in the pyriform and hippocampal cortices, i.e. zones of exclusively and predominantly olfactory projections respectively, and are considerably less pronounced in the dorsal cortex, the zone of predominantly visual afferentation.

Animals↗
PubMed1982

Correlation between the morpho-functional organization of some portions of the visual analyser of chelonia and their ecology: I. Normal morpho-functional characteristics of the optic nerve and the tectum opticum.

Several methods (light optic, electron microscope and electrophysiological) were used to study the optic nerve and the tectum opticum of water turtles (two species) and of land tortoises (two species). As the result of study of the two levels of the visual analyser in four species of Chelonia three groups of signs of the morpho-functional organization were distinguished: signs common for the Chelonia under study; ecologically specific signs--common for water turtles and species-specific traits which are--different in species of the same ecological group. Specific features of structural-functional organization of the visually directed behaviour in Chelonia at the neuronal populations level were shown to correlate with the ecological features to a greater degree than with the systematic position of the species.

Animals↗
PubMed1982

Correlations between the morpho-functional organization of some parts of visual analyzer and ecology in Chelonia: II. Morpho-functional characteristics of the visual nerve and tectum after unilateral enucleation.

The morpho-functional characteristics of the optic nerve and tectum opticum were studied electronmicroscopically and electrophysiologically after unilateral enucleation in 4 Chelonia species. Different types of degeneration of the myelinated and unmyelinated optic fibers and their endings in the tectum are revealed. Comparison of the types and times of the degeneration of retinal axons and their terminals with changes of the tectum evoked potentials at different times after enucleation gives ground to conclude that myelinated fibers produce nerve endings degenerating on the dark pattern and unmyelinated, all the remaining endings with the light, neurofilamentous, glycogenous, vesicular and other degeneration patterns. A stratal arrangement of the retino-tectal projections of various type fibers is demonstrated. Asynchrony of the process of degeneration of different groups of fibers and the relationship between the rate of degeneration and the diameter of myelinated fibers, as well as the absence of a relationship between the change pattern and the diameters of myelinated and unmyelinated axons are revealed. In land tortoises and water turtles differences are revealed in the set of major degeneration patterns and their endings also in the patterns of stratal distribution of various categories of the retinal fibers and tectum. A possible relationship is proposed between the above differences and ecological properties of the Chelonia groups under study. Also revealed are species-specific features of some substantial aspects of the morpho-functional organization of the levels of the visual analyzer in Chelonia.

Animals↗
PubMed1981

[Comparative study of the neuronal and synaptic organization of the tectum mesencephali in the Caspian (Clemmys caspica Gmel.) and pond (Emys orbicularis L.) tortoises].

The neuronal and synaptic organization of tectum opticum was studied in two species of tortoises (Clemmys caspica Gmel, and Emys orbicularis L.) by means of Nissl, Golgi and electron microscopical methods. The Clemmys caspica tectum differs from that of the Emys orbicularis in a greater diversity of neuronal composition; a greater variety and quantity of cells with short axons, the presence of neurons with relatively short dendrites, in a greater relative thickness of the upper and deep systems of horizontal neurons, in a small number of axo-axonal synapses in sublayer Ia, a more diverse composition of synaptic zones in sublayers IIa and IIb, the presence of axons in layers Ib and IIb with certain species specific features of degeneration, the pattern of localization of tectal ganglionic cell projections. The above mentioned specific features appear to be connected with the species differences of these tortoises.

Afferent Pathways↗
PubMed1980

[Effect of adaptation to altitude hypoxia on the nonspecific immunity indices, production of hemagglutinins and development of adjuvant arthritis in rats].

It was established in rat experiments that adaptation to altitude hypoxia leads to the enhancement of immune response to sheep red blood cells and to an increase in the serum lysozyme level. Adaptation to altitude hypoxia also suppresses adjuvant arthritis and prevents arthritis-induced inhibition of antibody production.

Acclimatization↗
PubMed1979

Comparative characterization of the basic forebrain cortical zones in Emys orbicularis (Linnaeus) and Testudo horsfieldi (Gray).

The neuronal and synaptic organization of forebrain basic cortical zones in Testudo horsfieldi and Emys orbicularis and their dendritic spines have been studied using Nissle, Golgi and electron microscopic methods. It has been shown by comparison of the results that the two spicies have marked differences in the structural organization of the forebrain cortical zones. The cortical formation in Testudo horsfieldi is different from that of Emys orbicularis in a greater diversity of neuronal types, smaller size of neurons, smaller cell density in each cortical zones, the presence of horizontal dendritic terminals in dorsomedial dorsal cortex, the absence of the large neurons in dorsomedial medial cortex, ect. Moreover, in both species the dorsomedial dorsal cortex in comparison with medial and lateral cortex is characterized by a marked complexity of the structural organization (diverse neuronal composition, the presence of the stellate cells, the highest cell density, the smallest neuronal size). The investigation of spines in the different dendritic levels (proximal, middle and distal) of neurons in three cortical basic zones has been shown that in both species it has been observed the tendency to increasing of the spine density from proximal to distal part of dendrite. at all dendritic levels noninvaginated forms of spines predominated. Invaginated spines were recorded at the proximal and middle levels of dendrites and contain more organelles and inclusions than noninvaginated spines. In Testudo horsfieldi and Emys orbicularis differences of spine thin structure and spine density in the cortical basic zones were revealed. Moreover, in both species the spines of dorsomedial dorsal cortex were more numerous, more variable in shape, more abundant in organelles. It was there that a bush-like distribution of spines was found which in evidently a special form of synaptic organization of cortical neurons. The above features of this cortical zone indicates a higher degree of differentiation, suggesting that the dorsomedial dorsal cortex is phylogenetic youth as compared with hippocampus and lobus pyriformis.

Animals↗
PubMed1978

[Immune response in rats and mice with adjuvant disease].

There were phasic changes of immune response in rats and mice with adjuvant disease: an increase of antibody production on the 7th day after the injection of complete Freund's adjuvant and its depression on the 21st day; there was also observed suppression of normal antibody production to O- and Vi-antigens of typhoid bacilli.

Agglutinins↗
PubMed1978

[Comparative analysis of the neuronal and synaptic organization of the mesencephalic visual center of Greek and steppe turtles].

The stratification, neuronal structure and synaptic organization of tectum opticum have been studied in two species of tortoises (Testudo graeca and Testudo horsfieldi, Gray) by means of Golgi methods and electron microscopy. The midbrain tectum in these closely related animals has some common properties, but at the same time it possesses certain species specific features. Their properties in common appear to be connected with the common ecology and closely systematic place of Testudo graeca and Testudo horsfieldi. The specific features appear to be connected with the species differences in visual behavior of these species.

Animals↗
PubMed1977

[Topography and cytoarchitectonics of the main cortical zones of the turtle forebrain].

The description of cytoarchitectonics and topography of the three principle cortical zones of the forebrain of Emys orbicularis reveals that the cortical structures in the species are precisely distinguished with respect to their neuronal characteristics, density and the situation of cellular elements. Emys orbicularis occupies an intermediate position among the species of the order Chelonia described in the literature as regards the level of development of the forebrain cellular structures. Emys orbicularis is less progressive in respect to the structure of telencephalic cortical formations than Testudo carolina and has a number of progressive properties as compared with Testudo geometrica. Testudo graeca seems to be close to Emys orbicularis in the development of forebrain cellular structures.

Animals↗
PubMed1977

[Disruption of the mechanisms of natural immunity in the initial stage of adjuvant disease in rats and guinea pigs].

Similar changes in the nonspecific immunity indices were noted in experiments on rats and guinea pigs with adjuvant disease: depression of blood serum bactericidal activity and increase of the lysozyme and complement level, as well as inhibition of the phagocytic activity of leukocytes and production of normal antibodies to O- and Vi-antigens of typhoid bacilli in rats. Changes in disturbances of natural immunity factors in adjuvant disease correlated with the severity of the process in both animal species.

Animals↗
PubMed1977

[Comparative characteristics of the dendritic spines of the 3 chief zones of the forebrain cortex of steppe and bog turtles].

A comparative study of dendritic spines in the principal cortical regions of the forebrain was performed for two turtle species by the Golgi and electron-microscopy methods. Common features of spines were revealed for every cortical region of both turtle species. Distribution peculiarities in the proximal, middle and distal sections of the spines, as well as their density, shape, length and ultrastructure were taken into account. Apart from similar features for two turtle species, there are some differences between spines of the same cortical region in Testudo horsfieldi and Emys orbicularis, which might be associated with ecological peculiarities of both species.

Animals↗
PubMed1977

[Ultrastructure of the mesencephalic visual center of the steppe turtle].

A layer-by-layer study of ultrastructural synaptic organization of mesencephalic optic centre (tectum opticum) of T. horsfieldi Gray was made. The predominating type of synaptic contacts is axo-dendritic, however, there are some axo-axonic synapses which are met most frequently in the regions where polysynaptic complexes and glomeneruli (sublayer Ib, sublayer IIa and the upper zone of layer III) are disposed. Axo-somatic contacts are localized virtually in all the neuronic types. In the external layers of the tectum opticum where the terminals of optic afferents are disposed, a considerable morphological variety of nerve terminals is revealed which are distinguished not only by their ultrastructural parameters but also by the character of organization in synaptic complexes at different levels of the cortical plates of the investigated centre.

Animals↗
PubMed1977

[Comparative characteristics of the dentritic spines of the 3 chief cortical zones of the steppe turtle forebrain].

A comparative study of the dendritic spines in three principal cortical zones of the turtle forebrain reveals certain patterns of spine distribution, length, shape and other specific morphological characters in every cortical region. The dorsal cortex spines show the highest density, the greatest length, the smallest head diameter, the largest number of mitochondria and invaginated spines. The above features markedly distinguish the dorsal cortex spines from the those of the medial and lateral cortex, which is associated with a more complex morpho-functional organization of this cortical region.

Animals↗