[Change in formation of the somatosensory cortex ultrastructure in rats due to hypergravity in pre- and postnatal ontogenesis].

Chronic action of gravity force of 2 G on pre- and postnatal rats up to day 75 of postnatal development gave rise to ultrastructural deviations in the somatosensory cortex (SSC) suggesting higher afferentation to SSC as compared with their counterparts at 1 g, more intensive synaptic transmission, afferent input by dendrites and neurons functioning with more frequent interneuronic contacts, glia activation and increased blood supply that altogether pointed to a permanent impact of elevated extero- and proprioceptive input throughout the time of SSC formation.

[Ultrastructure of dendritic spines in the somatosensory cortex of rat's brain following 5- and 33-day hypergravity].

Electron microscopy examination of layers III-IV in the somatosensory cortex of rat's brain following 5- and 33-day and repeated 5-day exposure to 2 G revealed ultrastructural changes in dendritic spines, synapses, axon terminals and nervous cell body suggesting their functional activation and increase of the afferent input from hindlimb mechanoreceptors Hypertrophy of the acicular apparatus (AA) due to hypergravity, growth of AA destruction as a result of 33-day exposure and its ample evidence after repeated 5-day exposure lead to the conclusion that AA ultrastructure can be used for assessing afferent input into the brain cortex of animals exposed in a changed field of gravity.

[Primary and repeated exposure to hypergravity: ultrastructure of the somatosensory cortex in rats].

Nineteen-day centrifugation of rats at 2 G and ensuing 30-d readaptation to 1 g caused changes in the somatosensory cortex (SSC) ultrastructure pointing to intensification of the afferent input and functional activity of SSC neurons during hypergravity, and recovery of these processes in the course of readaptation. Repeated 5-d centrifugation of the rats at 2 G produced changes in ultrastructure of SSC layers 3 and 4 evidencing a more effective cortex functioning aimed at facilitation of adaptation to hypergravity repeated after the lengthy delay.

[Ultrastructural changes in somatosensory cortex of albino rats during space flight].

For the first time, mammalian brain has been studied during space flight aboard NASA orbital laboratory Spacelab-2. The main ultrastructural differences in the somatosensory cortex of the brain fixed under microgravity conditions and after landing include an increased number of degenerating presynaptic axon terminals after landing. Apparently, this is due to a sharp increase in afferent impulsation in the cortex during and after landing.

[The acceleration of ultrastructure changes of synapses in somatosensory cortex of the rats at repeated simulation of weightlessness effects].

The electronmicroscopica/study of brain somatosensory cortex in the rats, exposed to postponed for a long time repeated lack of support load on hindlimbs by means of tail-suspension, has been revealed in hindlimb area of cortex the changes of ultrastructure of axodendritic synapses and neurons pointing out the acceleration of decrease in functional activity of synapses and neurons in 3-4 layers at postponed for a long time repeated simulation of weightlessness effects.

[Intermittent exposure to hypergravity of rats deprived of support to the hind limbs. analysis of the somatosensory cortex ultrastructure].

Intermittent hypergravity was evaluated as a method to prevent the unfavorable nervous effects of microgravity. It was shown that intermittent exposure to hypergravity (2 G, 1 h. a day) of rats during 24-d tail-suspension put a barrier to changes in the ultrastructure of the brain somatosensory cortex associated with a reduction in the afferent input to the somatosensory cortex from the hind limbs.

[Morphology of the rat's brain in and after a space flight: ultrastructure of the "blue spot"]. / Morfologiia golovnogo mozga krys vo vremia i posle kosmicheskogo poleta: ul'trastruktura sinego piatna.

Electron microscopy was used to explore ultrastructure of the livor extracted from the brain of rats on day-13 aboard U.S. space shuttle Columbia (STS-58), and in 5-6 hrs. after landing following the 14-d mission. As compared with the ground controls, the rats flown in microgravity reduced the total number of axodendrite synapses (ADS) by 21% and functional ADS--by 39.7%. After touchdown the total ADS number remained lowered by 16.5%; however, the percentage of highly active ADS exceeded this parameter in the ground controls. Results of the analysis of the ADS number in conjunction with the ultrastructural changes in axonal terminals and dendrites suggest a sharp decrease of the afferent influx towards the livor neurons during microgravity, whereas modifications of the livor neuron ultrastructure point to a decline in their functional activity. These data serve as an experimental proof of the hypothesized development of the hyponoradrenergic syndrome by mammals in microgravity.

[Morphometric study of yeast cells of Torulopsis sphaerica after He-Ne-laser irradiation]. / Mopfometricheskoe issledovanie drozhzhevykh kletok Torulopsis sphaerica posle oblucheniia svetom He-Ne-lazera.

A study was made of structural organization of Torulopsis sphaerica cells irradiated with He-Ne (lambda = 632.8 nm; dose--460 J/m2) and then cultured in the nutrient with 1% glucose and O2 for 6 h. The computer analysis of electron images of cell sections was carried out. Evidences of stimulation of cell proliferation were found, including decrease in the areas of cell and chondriome profiles, decrease in the number of mitochondria on sections, elongation of cells and mitochondria, and increased variability of cell parameters. In addition, cells of irradiated cultured were characterized by the increase in the number of mitochondria contacting the endoplasmic reticulum (in this case the outer mitochondrial membrane presumably associates with the ER membrane), which may suggest the activation of ATP synthesis. Thus, He-Ne laser irradiation activates cell metabolism even at the early stage of culture growth.

[Ultrastructure of the cortex of the cerebellar nodulus in rats after a flight on the biosatellite Kosmos-1514]. / Ul'trastruktura kory nodulusa mozzhechnika krys posle poleta na biosputnike "Kosmo-1514".

The ultrastructure of moss fibers and granule cells of the cortex of the cerebellum nodulus of rats flown for 5 days onboard the biosatellite Cosmos-1514 and exposed to 1 g for 6-8 hours upon return to Earth is indicative of an excess excitation of terminals of moss fibers and excitation of granule cells. The excitation of moss fiber terminals reflect the excitatory state of hair cells of the otolith apparatus and neurons of the vestibular ganglion produced by the effect of 1 g after exposure to microgravity. This state can be viewed as evidence of a greater sensitivity of the hair cell of the otolith organ--neuron of the vestibular ganglion system during exposure to microgravity. It is hypothesized that the sensitivity of this system of other mammals may also increase in microgravity.

[Distribution of myelinated fibers in the outer plexiform layer of the optic tectum in the frog, Rana temporaria]. / Raspredelenie mielinizirovannykh volokon v naruzhnom pleksiformnom sloe opticheskogo tektuma liagushki Rana temporaria.

Distribution of myelinated nervous fibers in the layer 9 of the optic tectum of the frog Rana temporaria has been investigated in normal animals as well as 6--9, 60 and 134 days after contralateral enucleation. Counts were made on long and oriented sections at the screen of electron microscope. Fields of myelinated fibers in the layer 9, visible under light microscopic, are not distinguished by higher density of these fibers and differ from the other parts of sections probably due to some qualitative differences, especially because of parallel orientation of these fibers within a field. In rostral part of the tectum, myelinated fiber density in the most superficial zone of the layer 9 (0--50 millimicrons from the outer surface) is higher as compared with central and caudal parts. After degeneration of myelinated optic fibers, there are many unchanged fibers of this type in the layer 9.

[Laminar analysis of the synaptic organization of the frog optic tectum]. / Posloinyi analiz sinapticheskoi organizatsii opticheskogo tektuma liagushki.

Distribution of axo-axonic and axo-dendritic synapses, nervous terminals and neuron somata in the depth of the optic tectum was studied in frog Rana temporaria L. in norm and 6-9, 60 and 134 days after contralateral eye enucleation. In outer plexiform layer 9 density of synapses was found to be maximal near the surface of the tectum; it decreased in deeper levels. In the outer zone of layer 9 (about 0.30 micrometer from the surface) many axo-axonic synapses were found. Terminals of myelinated optic fibres of large diameter ("dark" terminal degeneration) were widely distributed in layer 9. Density of axo-dendritic synapses in deep plexiform layer 5 was similar to that in layer 9. Numerous nervous terminals containing not only light synaptic vesicles, but also granular vesicles were seen in layer 5 and in adjacent zones.