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The appearance of autoantibodies to neuronal proteins (S100, GFAP, MBP, and NGF) in rat serum was analyzed by ELISA on days 5, 10, 17, 25, and 32 after streptozotocin injection. Simultaneously, blood glucose and insulin autoantibodies were assayed. Serum glucose level increased on the next day after streptozotocin injection and the level of autoantibodies to insulin significantly increased on day 5 indicating the development of diabetes. The levels of antibodies to specific neuronal proteins (S100, GFAP, MBP, and NGF) also increased at this term. It is concluded that diabetes with streptozotocin is associated with damage to the blood-brain barrier.

The mechanisms of early embryonic pathology of the brain in man and animals were studied. Analysis of the biomechanical properties of development of nervous tissue and embryonal experiments demonstsrated that tangential neuroepithelial intention is the major source of positional information. Experimental changes in the neuroepithelial intention system resulted in various types of embryonal anomalies of the nervous system. Mechanical-dependent ion channels that have marked periods of sensitivity and determine the histogenetic direction of neuroblast cell differentiation were found to underline the mechanosensitivity of the neuroepithelium. Experimental findings were compared with unique autopsy data on early development of the human brain. Human embryos were examined from neurulation to month 6 of development. Different types of human embryonal brain anomalies were shown to occur with 3 types of neurulation disordes: 1) an open preneuropore is responsible for anomalies of the forebrain and etmoidal area; 2) arrested neurulation in the postneuropore leads to anomalies of the diencephalons, midbrain, and occipital region; 3) impaired neurulatuion in the caudal region is a cause of spinal cord anomalies. The above anomalies resulted from local compensatory responses of the neuroepithelium due to the lack of intentions that are characteristic of normal development of the neural tube.

Principle trends in the evolution of brain associative centers are discussed. It is demonstrated that in various taxonomic groups the possibilities of adaptive changes, as far as the brain is concerned, go beyond the scope of biological, topographical, and dynamic coordinations, typical for other scopes and systems. The reason for such peculiarity of brain evolution is the multifunctional nature of nerve tissue. This property of nerve tissue allows vertebrates to implement the integrity principle and still preserve the flexibility of the brain, which is highly specialized morphologically and functionally.

Principal events in the early embryonic development of the nervous system, from neurulation to primary differentiation, are considered in different amphibian species. Attention is paid to numerous interspecific differences in the structure of neuroepithelium and the patterns of neurulation and embryonic brain segmentation. The data presented indicate that similarity in brain developmental patterns is apparently explained by universality of morphogenetic mechanisms rather than by the common origin of particular species. A hypothesis is proposed that similarity in the shape of the developing amphibian brain is determined by mechanisms of coding positional information necessary for histogenetic differentiation.

The mechanisms of early embryonal shaping of the brain in man and animals were studied. Analysis of the biomechanical properties of development of nervous tissue and embryological experiments demonstrated that tangential neuroepithelial intention is the major source of positional information. Experimental changes in the neuroepithelial intention system resulted in various types of embryonal anomalies of the nervous system. Mechanism-dependent ion channels that have marked periods of sensitivity and determine the histogenetic direction of neuroblast cell differentiation were found to underlie the mechanosensitivity of the neuroepithelium. Experimental findings were compared with unique autopsy data on early development of the human brain. Human embryos were examined from neurulation to week 6 of development. Different types of human embryonal brain anomalies were shown to occur with 3 types of neurulation disorders: 1) an open preneuropore is responsible for anomalies of the forebrain and ethmoidal area; 2) arrested neurulation in the postneuropore leads to anomalies of the diencephalon, midbrain, and occipital region; 3) impaired neurulation in the caudal region is a cause of spinal cord anomalies. The above anomalies resulted from local compensatory responses of the neuroepithelium due to the lack of intentions that are characteristic of normal development of the neural tube.

The effect of some developmental abnormalities on the morphogenesis of human brain asymmetry during early embryonic stages was studied. Insignificant predominance of the left hemisphere (1-3%) was revealed in human embryos.

Histological and morphometrical analysis of the brain and peripheral analyzers revealed proliferative migration abnormalities of brain development and neuron differentiation in mammals during a space flight, which can limit space exploration.

Amphibian embryos (Triturus vulgaris, Pleurodeles waltl, Hynobius keyserlingii, Ambystoma mexicanum, Rana temporaria, Bufo bufo, and Xenopus laevis) were investigated. We ascertained the morphological right-side asymmetry of the brain, which appears at the neurula stage and is preserved during the postembryonic (larval) development. In T. vulgaris, P. waltl, H. keyserlingii, and X. laevis, we observed right-side asymmetry of peripheral analyzers, such as the retina, ganglia of nerve VIII, and olfactory placodes. Structural analysis of the forebrain in A. mexicanum has shown that in the larvae, the pallium prevails on the left side of the cerebral hemisphere. During metamorphosis, left-side asymmetry is replaced by right-side, which is then preserved. We propose that the brain asymmetry arose at the early stages of evolution as a result of embryonic formation of the nervous system.

Results of experiments with biomechanical interactions of neuroepithelial cells from growing brain in various vertebrate taxa are analyzed. It is shown that neuroepithelium fulfills a number of mechanical functions at the stages of blastula, gastrula, neurula, and nerve tube. The cells develop mechanical tensions differing by their form, strength and duration. Tensions and compressions are resulted from local or global changes in the form of the cells possessing mechanical sensitiveness. Regular distribution of mechanical tensions and compression is related topologically to various zones of neurons differentiations. This allows to suppose mechanical dependence of processes of determination of the nerve system development at its earlier stages. The place of biomechanical interactions in the brain formation is considered in the framework of the evolution of structural organization of the vertebrate neuroepithelium.

Human embryos with anomalies of brain and spinal cord were studied on 27-35th day of the development. It was established that developmental anomalies were associated with the disturbed formation of neural tube. The reconstruction of three-dimensional brain arrangement of embryos has shown the presence of different variants of nonclosed medullar tori. In mild disturbance of neurulation, there is an acceleration of organogenesis and morphological differentiation induced by the shackening of normal mechanical tensions and relaxation of neuroepithelial layers. In presence of substantial parts of open neural tube, the development of brain and ectodermal derivatives becomes disturbed to be a possible cause of anencephaly and hypotelorism. The type of disturbed neurulation inducing developmental anomalies of nervous system is suggested to be a factor which determines forms of secondary craniofacial and cranial pathology.

Analysis of the experimental results on the embryonal nervous tissue transplantation into the various parts of the nervous system of animals and man is made in the review. Transplants in many experiments survive and differentiate even in transplantation between different species. Main problem is isolation of specific groups of donor cells, ensuring their survival and differentiation into a given direction in the host brain. The most favourable results are anticipated in the xenotransplantation when the donor cells are those of neural germs of insects and amphibia.

Meningoencephalic hernia was studied in human embryo at the 5th week (stage 15) of the development. The analysis of parietal hernia showed that the anomalous development of cerebral tissue was related with disturbed shape-forming processes in the nerve tube. The medullar toruli were not closed at the stage of nerve plate to form a free edge of neuroepithelial layer. Its relaxation resulted in a spontaneous foldness and an enhanced proliferation of neuroepithelial cells. The proliferative activity induced hyperplasia of the layer end zones a disproportionately rapid growth of the brain disturbed the integrity of cephalic ectoderm and elicited formation of external cerebral hernias. It was suggested that disturbances of tangential mechanical tensions which control the proliferative activity in the neuroepithelium underlie the overgrowth of nervous tissue.

The embryonic brain was dissected in urodele amphibians at the early postneurulation stages. Tangential mechanical tensions were shown to exist in the embryonic brain. The reaction of neuroepithelial cells characterizing the topology of tensions was found by the use of dissections in two interperpendicular directions. The cells were oriented along the acting force in the case of unidirectional tension. In the case of two interbalanced tensions the cells were inclined along the lines of force of greater tension. Three types of tangential tensions were revealed which differ in force, direction, range of action and life time. The life times of tangential tensions were shown to depend on their force and range of action. The strongest tensions were short-lived and, besides, limited in space. Weak tensions were long-lived and spread all over the brain. In all cases of dissections the cells inducing tangential tensions reacted in the same way: by elongation of cell bodies along the normals to the brain layer. It is suggested that the tendency of cell elongation can cause the tangential tension of the layer. It was found that the partial removal of tensions enhances the curvatures of brain layers. The cells reacted to the tension removal in accordance with their position in the layer. If the cells are located in the grooves, they are shortened. If the cells are outside the grooves, they are elongated. It was found that after the tension was removed the nuclei migrated along the cell bodies. The migration of the nuclei depends on the direction of the layer flexure. The nuclei always migrated to the external surface of evagination or to the internal surface of flexure. It is suggested that the tangential tensions stabilize the changes in the brain shape.