[Neuronal and glial antigen distribution in the columns of somatosensory cortex of rat brain (an immunohistochemical study)].

The aim of the study was to detect the neocortical columns in the S1 field on frontal sections of brain of albino rats using the method of immunohistochemistry and the antibodies against neuronal (synaptophysin, neurofilament) and gliocyte (glial fibrillary acidic protein--GFAP, myelin basic protein) proteins. The examination of the expression of the major neurospecific antigens revealed that on thin sections (4 micromin) a column could be identified due to accumulations of the astrocytes and neuronal processes--axons and dendrites. GFAP expression study also showed that cortical layer I usually contained multiple large astrocytes with branching processes, as well as numerous smaller processes with high intensity of expression. Synaptophysin content was high in all the layers of the cortex, but the most intense reaction was detected in the molecular layer, similarly with the intensity of GFAP reaction. The expression of myelin basic protein was detected in accordance with the radially extending myelinated processes of the neurons in the cortex.

[Analysis of spatial arrangement of gap junctions in respect to chemical synapses in the serial ultrathin sections of rat barrel cortex].

Electron microscopic investigation of gap junctions (GJ) on serial sections of rat barrel cortex has shown that GJ were in contact with one or both processes that formed chemical synapses, however, these connections could not traced in single sections. In the serial sections, it was possible to observe two GJ in the immediate proximity to one another, in a single field of vision, thus, each GJ was traced in two or three successive sections in a series. Considering the described variants of GJ arrangement in the cortex, it is suggested that GJ could be a structural basis for local synchronization of the bioelectrical activity not only at postsynaptic, but also at presynaptic level, and the formation of GJ occurs both before, and after the development of chemical synapses.

[Structural organization of the barrel cerebral cortex in rat (an immunohistochemical study)].

Immunohistochemical investigation of the regional distribution of neuronal and glial elements in the barrels of somatic cortex was carried out in rats (n=10). High level of synaptophysin protein expression was detected in the in barrel walls together with the accumulation of astroglial cells in their central areas. Ultrastructural investigation of chemical synapse structure showed the predominance of asymmetrical perforated axospinous contacts, presumably of excitatory type. The symmetric inhibitory synapses were more frequently located in the barrel walls in the areas of the denser neuronal perikarya distribution, as well as on the large dendritic processes. The number of vertically oriented myelinated axons within the barrels was found to be significantly greater than the number of the horizontally oriented interneuronal circuits.

[The role of gap junctions in the local rhythmogenesis in the cortical columns].

Ultrastructural characteristics of electrical dendro-dendritic synapses (gap junctions (GJ) of stellate neurons of D2-D3 barrels were detected and analyzed in the complex morpho-functional investigations of rat barrel cortex. Considering the local character of dendritic branching of the barrel cells, which is limited by the borders of a single column, it may be suggested that GJ which account for only 7% of the whole number of synapses, may be the structural base of local intracolumnar electrotonic synchronization of pacemaker hyperpolarisation potentials of barrel neurons during the development of spindle activity in the corresponding column.