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S L Kondrashev

Publications and source records attributed to S L Kondrashev.

9 recordsLinked to original sources
PubMed2003

Biplexiform ganglion cells in the retina of the perciform fish Pholidapus dybowskii revealed by HRP labeling from the optic nerve and optic tectum.

Using retrograde HRP labeling from the optic nerve (ON) or optic tectum (OT), we have visualized biplexiform cells in wholemounted retinas of the stichaeid fish Pholidapus dybowskii and studied their morphology and spatial properties. Biplexiform cells labeled from the ON were similar in their morphology to biplexiform cells found in other fishes. Their distribution across the retina was non-random and independent of that of other large ganglion cell types. Biplexiform cells labeled from the OT, too, formed non-random mosaics, whose spatial properties suggested that most or all biplexiform cells project to the OT in this species. We propose that biplexiform cells in Pholidapus are homologous to biplexiform cells in other fishes (lower vertebrates). Pholidapus biplexiform cells may participate in the tectum-mediated visual reactions.

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PubMed1999

Species-dependent variation in the dendritic stratification of apparently homologous retinal ganglion cell mosaics in two neoteleost fishes.

Large retinal ganglion cells of the marine neoteleost Bathymaster derjugini were labeled with horseradish peroxidase and studied in flatmounts. Four types formed regular, independent mosaics, of which three (biplexiform, alpha-a, alpha-c) resembled those in several other teleosts. The fourth (alpha-ab) appeared novel in one significant respect. Whereas we originally described similar cells in another neoteleost, Oreochromis spilurus, as monostratified in sublamina b of the inner plexiform layer, these were very clearly bistratified in a and b. Detailed re-analysis of our Oreochromis flatmounts showed that the difference is of one degree only: many Oreochromis cells do send fine dendrites into a. These observations strengthen the evidence that all four mosaics are homologous across a wide range of fishes, and clear away an obstacle to our earlier proposals that the alpha-a, alpha-ab and alpha-c mosaics of fishes, frogs, and perhaps other nonmammalian jawed vertebrates too, may all be homologous.

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PubMed1999

The effect of temperature on the light-induced pigment movement in fish corneal chromatophores.

Corneal chromatophores of unusual morphology were used for studies on the influence of temperature on the intracellular pigment movement in two species of marine fish from different temperature zones: the tropical puffer, Canthigaster cinctus, and boreal whitespotted greenling, Hexagrammos stelleri. It was shown that both dispersion under bright illumination and aggregation at darkening are slower or decrease at lower temperatures when examined in the range of 12-27 degrees C. The mean speed of the pigment translocations in the individual cell process was 0.38 micron/s at the highest temperature examined, with a range of 0.17-1.0 micron/s. Near the middle of the temperature range, the dynamic characteristics of cell pigment movement in tropical and boreal species were rather close, suggesting that there would be little divergent adaptations with respect to the mechanisms of the pigment transport. Corneal chromatophores are considered as a new promising model for cell motility studies.

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PubMedDate not supplied

Biplexiform ganglion cells, characterized by dendrites in both outer and inner plexiform layers, are regular, mosaic-forming elements of teleost fish retinae.

Biplexiform ganglion cells were labelled by retrograde transport of HRP in five species of marine fish from the neoteleost acanthopterygian orders Perciformes and Scorpaeniformes. Their forms and spatial distributions were studied in retinal flatmounts and thick sections. Biplexiform ganglion cells possessed sparsely branched, often varicose, dendrites that ramified through the inner nuclear layer (INL) to reach the outer plexiform layer (OPL), as well as conventional arborizations in the most sclerad part of the inner plexiform layer (IPL). Their somata were of above-average size and were displaced into the vitread border of the INL. Mean soma areas ranged from 99 +/- 6 microns2 in Bathymaster derjugini (Perciformes) to 241 +/- 12 microns2 in Hexagrammos stelleri (Scorpaeniformes), but were similar in each species to those of the outer-stratified alpha-like ganglion cells, whose dendritic trees occupied the same IPL sublamina. In the best-labelled specimens, biplexiform cells formed clear mosaics with spacings and degrees of regularity much like those of other large ganglion cells, but spatially independent of them. Biplexiform mosaics were plotted in three species, and analyzed by nearest-neighbor distance and spatial correlogram methods. The exclusion radius, an estimate of minimum mosaic spacing, ranged from 113 microns in Hexagrammos stelleri, through 150 microns in Ernogrammus hexagrammus (Perciformes), to 240 microns in Myoxocephalus stelleri (Scorpaeniformes). A spatial cross-correlogram analysis of the distributions of biplexiform and outer-stratified alpha-like cells in Hexagrammos demonstrated the spatial independence of their mosaics. Similar cells were previously observed not only in the freshwater cichlid Oreochromis spilurus (Perciformes) but also in the goldfish Carassius auratus (Cypriniformes) which, being an ostariophysan teleost, is only distantly related. Thus, biplexiform ganglion cells may be regular elements of all teleost fish retinae. Their functional role remains unknown.

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PubMedDate not supplied

[Contancy of color perception in the grey toad].

Under the conditions of behavioural experiment capacity of grey toads for constant perception of an object colour was studied. It is shown that irrespective of the spectral composition of light source toad males are able to recomgnize blue colorations among the other ones (green and grey of various gradations).

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PubMedDate not supplied

[Constancy of color perception in the gray toad (Bufo bufo L.)].

Colour vision and constancy of colour perception in Bufo bufo L, were examined by means of unconditioned reaction of choosing moving and stationary models of females by males during breeding season. The males chose blue and dark blue models. Control of the choice of blue models presented in pairs with models of different shades of grey proves the existence of colour vision in Bufo bufo L. The choice of blue models has been observed under significantly varying conditions: both with artificial illumination and in sunlight. This attests the capacity of toads for constant colour perception. When a model was presented against a saturated red background, colour contrast was observed: under such conditions the toads chose the grey models which evoked no reactions when presented against white background.

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