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A Bozhilova-Pastirova

Publications and source records attributed to A Bozhilova-Pastirova.

At least 19 recordsLinked to original sources
PubMed2000

The inferior oilvary complex.

Although many studies have established the connections of the inferior olivary complex, there have been relatively few studies on the morphology of this nuclear complex. On the base of the similar topographic relations and connections with the cerebellum, the inferior olivary complex is regarded as homologous in all vertebrates. We present comprehensive light microscopical qualitative and quantitative analysis of the inferior olivary complex in different representatives of submammilian and mammilian vertebrates, including human. A detailed comparison was made at the structural level. Cytoarchitecture and cellular morphology of the inferior olivary complex have been studied in several submammilian (carp, frog, lizard, tortoise, pigeon) and mammilian species (rat, cat, and for the first time ground squirrel Citellus citellus L), including human.

Animals↗
PubMed1999

Intramembranous structure of synaptic membranes with special reference to spinules in the rat sensorimotor cortex.

The intramembranous structure of the synaptic contact zone at presynaptic and postsynaptic membranes in the rat sensorimotor cortex was examined by means of the freeze-etching technique. In axospinous synapses, the synaptic contact zone is characterized by perforated and nonperforated aggregates of intramembranous particles at the extracellular half or E-face of the postsynaptic membrane. On some perforated synaptic contact zones, both synaptic membranes are marked by so called spinules. These invaginations of the postsynaptic membrane and the parallel presynaptic membrane into the axon terminal are situated at the particle free zones among the postsynaptic E-face intramembranous particle aggregates or in close proximity to it. Intramembranous characteristics of the spinules at both freeze-etched faces of presynaptic and postsynaptic membranes and their density of perforated axospinous synapses were analysed. The results are discussed in terms of plasticity at the synaptic contact zone of the axospinous synapses of the sensorimotor cortex in the rat.

Animals↗
PubMed1998

Sex and age differences of neurons expressing GABA-immunoreactivity in the rat bed nucleus of the stria terminalis.

Neurons, containing GABA were visualised immunohistochemically in the bed nucleus of the stria terminalis. Young prepubertal (20 days of age) and postpubertal (3 months and 1 year of age) Sprague-Dawley rats were used. Quantitative studies revealed greater density of GABA-immunoreactive perikarya in female than in male bed nucleus of the stria terminalis. This difference was not due to distribution in different volumes, since the volumes of the bed nucleus of the stria terminalis in the three ages studied did not differ by gender. Castration of new-born male rats caused elevation of the density of GABA-immunoreactive neurons in the bed nucleus of the stria terminalis to female levels on the third month of life. The percentage of nerve cells, expressing detectable amounts of GABA increased with age in the rat bed nucleus of the stria terminalis. The sexual dimorphism of GABA-immunoreactive neurons in the bed nucleus of the stria terminalis may contribute to the formation of reproductive behavior. The elevation of GABA expression with age might reflect change of the cellular activity in this part of the limbic circuitry.

Age Factors↗
PubMed1998

Effect of thymosin fraction five (TF5) on early neuroembryogenesis in the newt Triturus cristatus.

Thymosin fraction five (TF5), a well-characterized immunoregulatory thymic preparation, has been reported to stimulate corticotropin (ACTH) release. The present study explores the morphogenetic role of TF5 on early stages of nerve tissue formation during embryogenesis. In vivo TF5-treatment of newt embryos during neurulation results in stimulation of the process expressed at a macro-microscopical level by emphasizing the embryo's relief and by accelerating the neural tube closure. The stimulating effect of TF5 on neurulation is manifested ultrastructurally by enhanced apical endocytosis, a well-developed contractile microfilamentous layer, increased apical intercellular junctions and changes of the cytoplasmic organelles linked with the protein synthesis. The polymorphism of mitochondria and the morphological expression of enhanced yolk material assimilation confirm the idea of TF5-stimulating effect on the neuroepithelial cells.

Animals↗
PubMed1998

Freeze-etching study of the axosomatic synapses in the rat sensorimotor cortex.

The intramembranous structure of axosomatic synapses in the rat sensorimotor cortex was studied by means of thin sections and freeze-etched replicas. In thin sections, symmetric synaptic junctions were located on perikarya of pyramidal and non-pyramidal neurons. In freeze-etched preparations, the postsynaptic neuronal membrane exhibited the same structure as the surrounding nonjunctional membrane on both fracture faces. Probably this is the freeze-etching equivalent of symmetric axosomatic synapses. Asymmetric synapses were found on perikarya of non-pyramidal neurons. In freeze-etched replicas, the postsynaptic non-pyramidal neuronal membrane contains aggregates of particles on the extracellular half (E-face) as an intramembranous equivalent of asymmetric synapses. The particle packing density in these aggregates was measured and compared with that at the E-face of dendritic shaft and dendritic spine membranes. Intramembranous characteristics of the axosomatic synapses in the rat sensorimotor cortex are discussed in terms of plasticity of the synaptic contact zone.

Animals↗
PubMed1997

Distribution of GABA-immunoreactive nerve cells in the bed nucleus of the stria terminalis in male and female rats.

The distribution of GABA-immunoreactive neurons in the subnuclei of the rat bed nucleus of the stria terminalis (BST) was studied by means of GABA immunohistochemistry. For detection of GABA immunoreactivity we used polyclonal antibodies and silver intensification. We have compared the pattern of distribution of immunoreactive cells in male and female rats and found some sexual difference, that may underlie functional variety. Computer assisted quantitative analysis of GABA-immunoreactive neurons per mm2 showed statistically significant sex differences in the medial part of the BST (0.001 < P < 0.01). The difference in the BST as a whole was set at 0.05 < P < 0.1. Females had more numerous GABA-immunoreactive cells than males. The measuring of sex differences was done using double-tailed Student's t-test after submitting the data to ANOVA.

Analysis of Variance↗
PubMed1996

Intramembranous structure of the postsynaptic membrane in the rat sensorimotor cortex.

Intramembranous structure of the postsynaptic membrane of the axodendritic synapses in the rat sensorimotor cortex was examined by means of freeze-etching technique. Perforated and non-perforated aggregates of particles were found at the extracellular half (E-face) of the postsynaptic membrane. To study correlation between membrane structure and synaptic plasticity we compared size and particle packing density in both type aggregates of particles at the E-face of the postsynaptic dendritic spine membrane. The results are discussed in terms of plasticity on the synaptic contact zone (SCZ) at the postsynaptic membrane of the excitatory axospinous synapses.

Animals↗
PubMed1996

Structure of the synaptic junctions in the rat sensorimotor cortex. Freeze-etching study of axodendritic synapses.

The intramembranous structure of axodendritic synapses in the rat sensorimotor cortex was studied by means of freeze-etched replicas and thin sections. In thin sections, symmetric synaptic junctions were located on dendritic shafts. Examination of freeze-etched preparations supported the notion that the postsynaptic dendritic shaft membrane exhibited the same structure as the surrounding non-junctional membrane on both fracture faces. In thin sections, asymmetric perforated and non-perforated synapses were found on dendritic spines and dendritic shafts. In freeze-etched replicas, the postsynaptic membrane of the dendritic spine and some of the dendritic shaft synapses were characterized by perforated and non-perforated aggregates of intramembranous particles at the extracellular half (E-face). These aggregates are accepted as a freeze-etch equivalent of perforated and non-perforated asymmetric synapses seen in thin sections. The intramembranous characteristics of axodendritic synapses in the rat sensorimotor cortex are discussed in terms of synaptic contact zone plasticity.

Animals↗
PubMed1995

Structure of the synaptic junctions in the rat sensorimotor cortex: freeze-etching study of neuronal gap junctions.

The membrane structure of neuronal gap junctions in the rat sensorimotor cortex was examined using freeze-etched replicas. The gap junction coupling was found between large, probably non-pyramidal neurons and dendrites, and was mostly associated with membrane specializations indicative of the contact zone of an asymmetric synapse or a puncta adhaerentia. The validity of freeze-etching method of identification and analysis of neuronal gap junctions as a feature of the synaptic organization in the rat sensorimotor cortex is discussed.

Animals↗
PubMed1995

Changes in the neuronal plasma membrane during synaptogenesis.

During synaptogenesis the plasma membrane of neurons undergoes considerable changes and large portions of it develop to synaptic membranes. This transformation is brought about by biochemical and morphological changes. The aim of the present investigation was to study by morphological methods the in vivo changes of some basic components of the neuronal membranes during the early postnatal period, when active synaptogenesis occurs. The cerebral cortex of Wistar rats was used for preparation of either growth cones (up to postnatal day 10) or synaptosomes (postnatal days 14-30). Our studies were focused on the changes occurring in integral membrane proteins and cholesterol domains, and in certain carbohydrate residues and anionic sites. In the first days after birth relatively few intramembranous particles are found in the plasma membranes of growth cones, few and small cholesterol domains, scarce lectin-binding and anionic sites. During the following days there is a clear tendency for increase of the number of all of the studied structures until the appearance of typical synaptic membranes. Throughout the studied developmental period the protein and the cholesterol molecules were found to occupy distinct membrane domains. The structure of the developing neuronal membrane, poor on proteins and cholesterol, and its maturation to the fully functional synaptic membrane is discussed.

Age Factors↗
PubMed1991

[The morphology of the glial cells in the inferior olivary complex of ground squirrels (Citellus citellus L.). I. Oligodendrocytes].

The morphological characteristics of oligodendrocytes in the lower olivary complex of ground squirrels at various ages were studied by light and electron microscopes. On the basis of an analysis on thick sections, stained with toluidine blue, it was established that nuclei of these cells were smaller and darker in comparison with those of astrocytes. The mean oligodendrocytes, located in perineuronal, perifascicular, perineuronal-perifascicular, interfascicular, perivascular position or freely situated, predominated in the neuropile of the lower olivary complex. Changes in their ultrastructure were investigated during advancement of age and during the process of aging. An increase in the number of heterogeneous dense bodies were found as well as the presence of lipid-pigmented granules with crystal-like brightening. The connection of oligodendrocyte growth with myelin sheath of axons.

Aging↗
PubMed1990

[A structural and ultrastructural study of the inferior olivary complex in ground squirrels (Citellus citellus L.)].

Morphological characteristics of neurons in the inferior olivary complex of ground squirrels at various ages were studied by a light and electron microscope. This nuclear complex consists of three nuclei: medial accessory olivary nucleus, dorsal accessory olivary nucleus and main olivary nucleus. Its cytoarchitectonics cytoarchitecture was studied by serial sections at the coronary level, stained by kresyl-violet. Two types of olivary neurons were established by silver impregnation in accordance with dendrite ramifications. Nematosomes, special forms of granulated endoplasmic reticulum, which could be probably connected with advancement of age and the process of aging were observed by an electron microscope together with organelles and intranuclear inclusions typical for the relay neurons.

Aging↗
PubMed1990

[The ultrastructure of the inferior olivary complex in ground squirrels (Citellus citellus L.). The neuropil. Age-related changes in the axons].

The morphological characteristics of axon terminals among a neuropil in the lower olivary complex of ground squirrels at various ages were studied by an electron microscope. The presynaptic part of the chemical synapses in the glomerular or outside glomerular position among the neuropil pf this nuclear complex were axon terminals and terminals "en passant". These axon elements participate in the formation of crash-like synapses with somatic, dendrite prickles, but also with dendrite adjuncts in the formation of complex synaptic connections. A considerable part of myelin axons and axon terminal were changed in old ground squirrels during all seasons. There were two varieties: 1. axon elements with preserved sizes and dense bodies, myelin-like figures, a large number of mitochondria and glycogen granules were found among normal organoids. 2. myelin and amyelin "spheroids" with various sizes and inner structure. The changes axon elements of the neuropil in the inferior olivary complex of ground squirrels at various ages during all seasons are physiological probably connected with the process of aging.

Aging↗
PubMed1990

[Ultrastructural research on the sensorimotor cortex in adult rats. I. Intranuclear inclusions in the neurons and astrocytes].

The morphological peculiarities of neurones and astrocytes in the sensorimotor cortex of mature (over 3 months) and elderly (over 24 months) rats were studied at electron microscopic level. Intranuclear inclusions are found in the nuclei of pyramidal neurones from the third and fifth layer. On the basis of their fine structure they could be grouped into the following types: 1. Filamentous bundles. 2. Filamentous crystalloids. 3. Granulofilamentous bodies. 4. Membrane-enclosed inclusions. 5. Combined intranuclear inclusions. Filamentous crystalloids are found in two varieties, composed of filaments with various diameter and way of arrangement. Membrane-enclosed bodies are formed as small vesicles or large vacuoles. Combinations from various types of inclusions in the nucleus of a neurone are discovered frequently. Only intranuclear inclusions of the type of membrane-enclosed bodies are observed in the nuclei of astrocytes. These bodies are found only in the nuclei of astrocytes of elderly animals. On the basis of the comparative analysis between ultrastructural characteristics and frequency of intranuclear inclusions in pyramidal neurones and astrocytes in sensorimotor cortex of mature and elderly rats their probable connection with age changes in the central nervous system is discussed.

Aging↗
PubMed1990

[Free postsynaptic-like compactions in the inferior olivary complex of the suslik (Citellus citellus L.)].

The morphological peculiarities of the neuropil [correction of neuropapilea] in the inferior olivary complex of young and elderly ground squirrels were studied by and electron microscope during periods of hibernation and waking. In some of the distal and middle dendrites and dendritic spines [correction of prickles] in elderly ground squirrels there were plaques, composed of electron-dense material with structure similar to postsynaptic condensations, but without presynaptic specializations of chemical synapses. The free postsynaptic-like condensations are located usually in dendrites, which fit to the cellular bodies and sprouts of oligodendrocytes, myelin sheath of nerve fibers and more rarely to astrocytes or lamellae and in single cases to neuronal perikaryon. The significance of the free postsynaptic-like condensations and their connection with age changes in the central nervous system is discussed on the basis of the comparative analysis of the morphological characteristics of the neuropil [correction of neuropapilea] in young and elderly ground squirrels during various seasons.

Animals↗
PubMed1990

[The ultrastructure of the inferior olivary complex in the ground squirrel (Citellus citellus L.). Age-related changes in the neurons].

The morphological characteristics of neurones in the lower olivary complex of ground squirrels at various age were studied by electron microscope. Some peculiarities in the ultrastructure of these neurones were described as the presence of prickles, fringes. Changes which occurred with advancement of age, were studied such as: an increase in the number of intranuclear inclusions, an accumulation of a large amount of elderly pigment under the form of lipofudcinis, lamellar bodies, myelin-like figures, vacuole-like bodies and nucleolus-like inclusions, called also nematosomes. On the basis of the analysis of ultrastructural peculiarities of neurones in the lower olivary complex of ground squirrels at various age the changes, which occurred during various functional states and during aging, are discussed.

Aging↗
PubMed1990

[The ultrastructure of the inferior olivary complex in the ground squirrel (Citellus citellus L.). Are-related changes in the dendrites].

The morphological characteristics of the elements of the neuropile in the lower olivary complex in ground squirrels at various age were studied by an electron microscope. The peculiarities in the ultrastructure of dendrite profiles, synaptic contacts on their surface and in the content of the complex synaptic connections and glomeruli. In this nuclear complex of ground squirrels--under the conditions of hibernation as well as in old very obese ground squirrels during all seasons there were a series of changes in the ultrastructure of dendrites such as: myelin-like figures, a large number of vacuoles, an accumulation of elderly pigment at the base of proximal dendrites and free postsynaptic-like condensations C. The changes in the dendrites, which occur during various functional states as well during aging, are discussed on the basis of the analysis on ultrastructural peculiarities of elements of the neuropile in the lower olivary complex in ground squirrels at various age.

Aging↗