[Localization of crystallins in Muellerian cells in the grass frog retina]. / Lokalizatsiia kristallinov v miullerovskikh kletkakh setchatki travianoi liagushki.

Cell localization of 23 kDa- and 35 kDa-crystallins in the retina of adult common frogs Rana temporaria L. was studied using indirect immunofluorescence. Intense specific fluorescence of both crystallins was observed all over the retina, in both periphery and central area. It was localized in elongated radially oriented cells, whose bodies were located in the inner nuclear layer. These cells gave many fluorescing processes in the same layer and main processes in the outer nuclear and ganglion layers, one in each. The processes formed a strong network of fibers around the photoreceptor and ganglion cells. Intense fluorescence was also observed in the layer of nerve fibers and adjoining inner limiting membrane. The distribution and morphology of crystalline-containing cells mostly coincides with what is known for the Muller cells of vertebrate eye. The identity of the cells we described and Muller cells was also confirmed using the antiserum to glial fibrillary acidic protein.

[The effect of para-aminobenzoic acid on the level of proliferative activity in the regenerating cornea of adult rats (a radioautographic study)]. / Vliianie paraaminobenzoinoi kisloty na uroven' proliferativnoi aktivnosti v regeneriruiushchei rogovitse vzroslykh krys (radioavtograficheskoe issledovanie).

[3H]-Thymidine radioautography showed that 0.005% p-aminobensoic acid (PABA) solution applied three times per day on penetrating wounds in central part of the adult rat cornea selectively stimulates proliferative activity of corneal stroma keratoblasts. In control rats, a curve showing changes in index of labeled nuclei in corneal stroma had two peaks, on the second and sixth day after injury (about 5 and 3%, respectively), whereas in animals receiving PABA treatment it had a single peak on the second day (about 12%). On days 7-14, indices of labeled nuclei in corneal stroma of both experimental and control rats become similarly low. No difference between experimental and control animals was revealed in indices of labeled nuclei in corneal epithelium: in both groups, corresponding curves had two peaks (about 9%) on the first and fifths days, and proliferation still continued two weeks after injury.

[Melanotropic activity in the hypophysis and blood of Wistar rats in early postnatal development]. / Melanotropnaia aktivnost' v gipofize i krovi u krys linii Vistar v rannem postnatal'nom razvitii.

The activity of melanotropins in pituitary homogenates and blood of Wistar rats obtained from the nursery Stolbovaia (Russian Academy of Medical Sciences) was studied using the method of biological testing (Hogben, Slome, 1931; Golichenkov, 1980). In order to elucidate, to what extent the normal status of melanotropic activity is retained in albino rats, two experimental series were performed. Melanotropic activity was determined in (1) intact rats and (2) in rats receiving subcutaneous injections of parachlorophenylalanine, a specific inhibitor of serotonin synthesis. Melanotropic activity of Wistar rats hypophysis during the studied period of development was similar to that of normal pigmented rats. However, the peak of melanotropic activity of blood which is characteristically observed in pigmented rats on day 3 of postnatal development is absent in the case of Wistar rats. The experimentally induced decrease in the serotonin level did not result in the increased melanotropic activity of blood. These data suggest that certain structures of hypophysis responsible for MSH secretion can be disturbed in Wistar rats. A short-term peak of blood MSH in rats during the first week after birth is known to provide for maturation of dopaminergic neurons located in the arcuate nucleus of the hypothalamus. Consequently, the absence of such peak in Wistar rats should result in neuroendocrine disturbances such as inadequate functioning of dopaminergic neurons responsible for melanotropin secretion by hypophysis beginning from the second week after birth (Lichtensteiger, Schlumpf, 1986).

[Emoxipin as an inhibitor of angiogenesis]. / Emoksipin kak ingibitor angiogeneza.

The effect of emoxypin on angiogenesis in rabbit cornea in aseptic inflammation induced by intracorneal implantation of a piece of quartz and on the development of the vessels of the chick embryo yolk sac was studied. 1% emoxypin pipetted thrice a day for 10-14 days inhibited corneal neovascularization and reduced the formation of new blood vessels. We observed an inhibitory effect on the development of vascular bed of the embryo yolk sac on incubation hour 64-72. The drug affected neither general growth of the embryos no the number of somites.

Image analysis of the lens opacities induced in developing chick embryo by glucocorticoid.

Glucocorticoid-induced cataracts in chick embryos were monitored by an image analysis system. Opacities in the lens visually showed a complex pattern with significant changes in the cortical and nuclear regions. An electronic image analyser produced an image in which contrast represented different zones of lens opacification in the frontal plane and documented objective lens findings such as the precise topography of the opacities, density and opacity measurements, geometric measurements of boundary surfaces and of regional areas. Parameters of lens clouding were evaluated quantitatively by measuring the optical density index and the area of the zones of clouding outlined with equi-densities. The light intensity standard graded different morphological areas of the lens into up to 256 grey levels. The data were entered and stored quantitatively into a computer. The lens images thus picked up by the TV camera and digitally stored in a frame buffer of the measuring system could be reliably transformed into a 2-D or 3-D picture of lens clouding. The approach demonstrated by the current study provides a sensitive and meaningful measure of cataractous changes for lens laboratory research.

[Immunohistochemical study of fibronectin localization during the formation of the vascular coat under the influence of the pigment epithelium in chick embryos]. / Immunogistokhimicheskoe issledovanie lokalizatsii fibronektina pri formirovanii sosudistoi obolochki pod vliianiem pigmentnogo épiteliia u kurinykh zarodyshei.

The role of fibronectin (FN) in cell interactions of retinal pigment epithelium (RPE) and mesenchyme surrounding the optic cup during choroid formation in chick embryos was studied by indirect immunofluorescence using antibodies against FN. Experimental coloboma of retina and choroid was used as a model. During the initial stages of coloboma the regions structured like retina rudiment appear in the outer layer of the optic cup. Such regions were formed in microphthalmic eyes obtained by excision of lens from the eyes of 3.5 day old chick embryos (stage 21). At stage 21 bright FN-specific immunofluorescence was observed in basal membrane located along the external surface of the normally differentiated RPE. Later on, FN-specific immunofluorescence appeared in mesenchyme condensing along the RPE. The most intensive FN-specific immunofluorescence was observed in chorio-capillary layer of choroid after 5-7 days of incubation. In microphthalmic eyes retina-like regions of RPE and adjacent mesenchyme showed negative reaction, and the choroid was not formed from the adjacent mesenchyme in such zones. The data obtained suggest that the presence of normally differentiated RPE producing FN-containing basal membrane is necessary for the formation of chorio-capillary layer of the choroid in chick embryos.

[Specific and nonspecific adhesion in the process of retinal cellular aggregation in chick embryos]. / Issledovanie spetsificheskoi i nespetsificheskoi adgezii v protsesse agregatsii kletok setchatki kurinykh zarodyshei.

A study of aggregation of the retinal cells of 8 and 14 day old chick embryos has revealed two phases in this process. The first phase includes the decrease in the concentration of single cells and the increase in the concentration of aggregates. During the second phase the concentration of aggregates falls at the expense of fusion of smaller aggregates into larger ones. The rate of aggregation at both these phases increases with the initial density of cells and decreases with the age of donor embryos and at a suboptimal temperature of cultivation. Aggregation during the first phase does not depend on the presence in the culture medium of divalent cations and colchicine, the level of protein and RNA synthesis in the cells, whereas aggregation during the second phase depends on all these factors. Comparison of these results with the published data suggests that the retinal cell aggregation during the second phase, unlike the first one, is based on the specific adhesiveness of the cells, which is realized via adhesion molecules resynthesized at the cell surface.

[Biochemical characteristics of adhesion factors isolated from the retina of 8-day-old chick embryos]. / Biokhimicheskaia kharakteristika faktorov adgezii, vydelennykh iz setchatki 8-sutochnykh kurinykh zarodyshei.

While isoelectrofocusing the extracts obtained after dissociation of the retina of eight day old chick embryos, two active protein fractions were found: AF I with pI 3 and AF II with pI below 3. The content of these fractions in the extracts depended on the method of dissociation: treatment with EDTA increased the content of AF II, whereas trypsin treatment increased the yield of AF I. After electrophoresis in the denaturating conditions both fractions were divided in two components. The effect of AF I on aggregation of retinal cells, unlike that of AF II, does not depend on the presence of bivalent cations in the medium and is realized within 1 h of interaction with the cells at 4 degrees. It is suggested that the retinal extracts of eight day old chick embryos contain substances providing two types of adhesiveness: Ca2+-independent (AF I) and Ca2+-dependent (AF II).

[Role of calcium-dependent and calcium-independent mechanisms in the adhesion of retinal and pigment epithelium cells in the chick embryo]. / Rol' kal'tsii-zavisimogo i kal'tsii-nezavisimogo mekhanizmov v adgezii kletok setchatki i pigmentnogo épiteliia kurinykh zarodyshei.

The mechanisms of adhesion of the retinal and pigment epithelium cells, as well of cell interaction within each of these tissues were studied during development. It was shown by means of separation of retina from pigment epithelium in different dissociation media that the adhesion of these tissues in 5-6 day old chick embryos is realized via a Ca2+-independent mechanism. The adhesion of these tissues decreases between days 7 and 16. Starting from day 16, both Ca2+-independent and Ca2+-dependent mechanisms are involved in the interaction of the retinal and pigment epithelium cells. By measuring the output of single cells into the suspension after the treatment of retina and pigment epithelium with different dissociating agents, it was shown that from the 5th day of incubation on the adhesion of pigment epithelium cells is mediated by Ca2+-dependent mechanism. In the retina three types of cells were found: interacting via Ca2+-dependent mechanism only, Ca2+-independent mechanism only, and both the mechanisms. In the course of differentiation, the numbers of the population of cells interacting only via Ca2+-dependent mechanism increase, while those of cells interacting via Ca2+-independent mechanism decrease. It is suggested that at each developmental stage those retinal cell possess Ca2+-dependent mechanism of adhesion which are closest to the definitive state.

[Role of Bruch's membrane in the process of metaplasia of the ocular pigmented epithelium of Xenopus laevis]. / Rol' membrana Brukha v protsesse stimuliatsii metaplazii pigmentnogo épiteliia glaza u shportsevoi liagushki

The metaplasia of pigmented epithelium into retina with the formation of nuclear and reticular layers took place in the experiments with wrapping a sheet of pigmented epithelium from tadpoles up in the Bruch's membrane of adult frogs X. laevis. The implant with de novo formed retina resembled the inverted eye. In those experiments where the Bruch's membrane of tadpoles came into contact with that of adults only depigmentation of the pigmented epithelium cells was observed. The pigmented epithelium metaplasia suggests that the Bruch's membrane is permeable not only for low molecular weight substances, but also for inducing agents. The adult Bruch's membrane serves in the process of metaplasia in the experiments described as a new and limiting system which ensures more orderly formation of new retina.

[Metaplastic transformation of the tissue of the eye in tadpoles and adult Xenopus laevis frogs]. / Metaplasticheskie prevrashcheniia tkanei glaza u golovastikov i vzroslykh shportsevykh liagushek

The pigment epithelium of the tadpoles and adults X. laevis, as well as of other anurans and cyprinids, is not capable of transformation into the retina without the special influences of agents produced by the retina. When implanting a layer of pigmented epithelium of tadpoles with the Bruch's membrane into the cavity of lensless eye of a tadpole, the transformation of pigment epithelium into retina proceeded in 40% of cases and when implanting the pigment epithelium of adults without the Bruch's membrane, the transformation proceeded in 68% of cases. The lens regeneration from the cornea which proceeds simultaneously under the retina influence exerted no effect upon the metaplasia of pigmented epithelium.

[The development of differentiation of pigment epithelium in teleosts and its stimulation to metaplasia]. / Stanovlenie differentsirovki pigmentnogo épiteliia i stimuliatsiia ego metaplazii u kostnykh ryb

The time was determined when pigmented epithelium acquires stable differentiation and the possibility was investigated for pigmented epithelium to transform in retina at different developmental stages in the Issyk-kul chebatchok Leuciscus bergi (Cyprinidae). By means of implantation of a layer of pigmented epithelium in pericardium it was established that the pigmented epithelium cells acquired stable differentiation rather early. When an already pigmented layer of pigmented epithelium was implanted in the cavity of a lensless eye, its cell transformed in retina under the influence of the whole retina. Conditions of pigmented epithelium metaplasia in retina in teleosteans proved to be similar with those for frogs.