[Hormone-Induced In Vitro Maturation and Ovulation of Danio rerio Oocytes and Production of Eggs Capable of Fertilization and Futher Development].

It is common knowledge that zebrafish, Danio rerio, oocytes in their follicular envelope that have reached definitive size undergo in vitro maturation in 90% Leibovitz’s medium, pH 9.0, when treated with 17α,20β-dihydroxyprogesterone and acquire developmental competence but do not ovulate (Seki et al., 2008).

[Hormonal Induction of In Vitro Maturation and Ovulation of Loach Oocytes and Obtaining Egg Cells Capable of Fertilization and Development].

Loach oocytes that have reached a definitive size and are surrounded by follicular envelopes are capable of maturation and ovulating under the effect of 1 μg/mL progesterone in 75% Leibovitz medium with 1 g/L sodium bicarbonate or with pH adjustment to 9.0 by 1 N sodium hydroxide. Inseminated eggs are developed until the stage of when adding 20% bovine serum to the incubation medium.

[Nonhormonal stimulation in vitro of oocyte maturation in sturgeons].

Incubation of sturgeon full-grown ovarian follicles in amphibian Ringer solution with increased sodium bicarbonate concentration results in "spontaneous" oocyte maturation. Addition of sodium bicarbonate to diluted Leibovitz medium also induces maturation of follicle-enclosed oocytes. Effective threshold concentration of sodium bicarbonate depends on the composition of culture medium and, especially, on the physiological state of follicle-enclosed oocytes.

[Role of hydration in ovulation of common frog oocytes in vitro].

Stimulation of ovulation of the common frog Rana temporaria oocytes with homologous pituitary extract caused an increase in their volume. Factors that are known to inhibit hydration in teleostean oocytes (potassium-free Ringer solution and inhibitor of Na+, K(+)-ATPase--ouabain), as well as use of aquaporin inhibitors (mercuric chloride and methylmethanethiosulphonate) inhibited also homologous pituitary extract-induced volume increase in follicle-enclosed oocytes and let to reduced percentage of ovulated oocytes. Volume of denuded oocytes remained unchanged in the course of maturation when exposed to progesterone or other treatments.

[Stimulation in vitro of oocytes of acipenserids with progesterone and homologous gonadotropic hormone of hypophysis].

We showed that the percentage of oocytes of acipenserids ovulating in vitro in Ringer solution modified for sturgeons (RMS) considerably depends on the concentration of sodium bicarbonate and the concentration of progesterone. Under optimal conditions (0.5 g/L of sodium bicarbonate and 30 ng/mL of progesterone), it can be higher than 80.

[Hydration of oocytes in bony fishes].

Data are collected on the hydration of oocytes in bony fishes during maturation stimulated by gonadotropic or steroid hormones in vivo and in vitro. The reasons for hydration, its dynamics, and certain of the mechanisms ensuring income of water and ions into the oocyte are considered.

[In vitro stimulation of oocyte ovulation in teleosts by gonadotropic and steroid hormones].

Published data on in vitro stimulation of oocyte maturation and ovulation by gonadotropic and steroid hormones in different teleost species are reviewed. The involvement of meiosis-inducing steroids, eicosanoids, and nuclear progesterone receptor in the mechanism of ovulation induction is considered.

[Aquaporins in gametogenesis of vertebrate animals].

A review of the data on the presence, localization, and supposed role of aquaporin water channels in oocytes of Xenopus laevis, oogenesis and maturation of teleosts Sparus auratus and Oncorhynchus mykiss, oogenesis and oocyte maturation of rats and mice, and spermatogenesis of several mammalians.

[Influence of culture medium osmolality on maturation and ovulation of Rana temporaria oocytes stimulated in vitro by the pituitary gland extract or progesterone].

The influence of diluted Ringer solution on ovulation and maturation of common frog oocytes stimulated in vitro by homologous pituitary extract (0.005 pit/ml) or progesterone (1 pg/ml) was studied. During wintering, the dilution of Ringer solution led to a decreased percentage of oocytes ovulated and matured under the influence of both inducers.

[Involvement of gap junctions in stimulation of in vitro maturation of the common frog oocytes by low progesterone concentrations].

The inhibitor of gap junctions 18alpha-glycerretinic acid inhibits the maturation of follicle-enclosed common frog oocytes stimulated by low progesterone concentrations. The inhibitory effect of 18alpha-glycerretinic acid does not depend on concentrations within the limits of 5-40 microM. The inhibitory progesterone concentrations differ markedly in different females.

[Maturation of the follicle-enclosed common frog oocytes stimulated by low progesterone concentrations depends on transcription].

The maturation of follicle-enclosed common frog oocytes stimulated by low progesterone concentration is inhibited by actinomycin D (5 micrograms/ml). The concentrations of progesterone, at which oocyte maturation was inhibited by actinomycin D, varied with the season and were different in different females. The inhibitor of steroidogenesis aminogluthetimide (100 micrograms/ml) did not suppress the maturation of follicle-enclosed oocytes in most experiments, which was induced by both high and low progesterone concentrations.

[Effects of the antagonist of the classical progesterone receptor on ovulation and maturation of common frog (Rana temporaria L.) oocytes in vitro].

Progesterone induces maturation and ovulation of amphibian oocytes and, in the process, binds to the receptors in oocytes and follicle cells. It is still unclear to what extent the progesterone receptors in these cells are similar. We tried to answer this question using RU486, an antagonist of the classical mammalian progesterone receptor.

[The role of chloride channels and chloride ions in steroidogenesis regulation in the gonads of amphibians, birds and mammals].

The paper represents the first review of data on the involvement of chloride channels (their inhibitors and media, in which chloride ions are substituted for anions that poorly penetrate in the cell) in the regulation of basal and gonadotropin-stimulated steroidogenesis in the gonads of amphibians, birds, and mammals. Possible causes are considered for different reactions of the gonad steroidogenic cells in representatives of different vertebrate classes to a decreased medium concentration of chloride and the involvement of chloride channels and/or chloride ions in the regulation of steroidogenesis is discussed.

[Role of protein kinase A and calcium ions in regulating ovulation of oocytes by gonadotropins in the grass frog (Rana temporaria) in vitro].

The inhibitor of cAMP-dependent protein kinase N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide (H-8) (12.5-50 microM) decreased the rate of ovulation of the follicle-enclosed Rana temporaria oocytes induced by the homologous pituitary extract in amphibian Ringer solution and in a chloride-free medium. The inhibitor of voltage-dependent calcium channels diltiazem (10 and 100 microM) decreased the rate of ovulation in Ringer solution but did not affect it in a chloride-free medium or decreased the ovulation inhibitory effect of this medium.

[The effect of the composition of the medium on the concentration of free calcium ions in the cells of the follicular wall in the common frog and in the clawed toad].

The concentration of intracellular free calcium ions in the follicle wall cells and in the follicle cells of Rana temporaria in Ringer solution is 150 +/- 10 and in the follicle wall cells of Xenopus laevis, 220 +/- 10 nM. In a chloride-free saline, its concentration in the same cells is 2.5-3 times that in Ringer solution.

Exclusively juvenile centrioles in Xenopus laevis oocytes injected with preparations of mature centrioles.

Activated oocytes of Xenopus laevis were injected with centriole preparations isolated either from spermatozoa of loach fish Misgurnus fossilis or from rat liver. These injections induced the development of cytasters in the ooplasm and egg cleavage. Electron microscopic study of cytasters was made at the stage that corresponded to interphase between first and second cleavage divisions.

[Effect of a chloride channel inhibitor and chloride-free medium on choriogonin-induced cAMP formation by Xenopus laevis follicles].

The inhibitor of chloride channels DIDS (10 microM) decreased and a chloride-free medium increased the cAMP level in the Xenopus laevis follicles stimulated by human chorionic gonadotropin. Also, DIDS inhibited while the chloride-free medium stimulated maturation of the follicle-enclosed oocytes.

Involvement of chloride channels in progesterone production during meiotic maturation of follicle-enclosed oocytes of Rana temporaria and Xenopus laevis.

The chloride channel blockers SITS (4-acetamido-4'-isothiocyanostibene-2,2'-disulphonic acid) and DIDS (4,4'-diisothiocyanostilbene-2,2'-disulphonic acid) markedly suppressed progesterone production in the Rana temporaria and Xenopus laevis follicle-enclosed oocytes and oocyte maturation stimulated by the homologous pituitary suspension and hCG, respectively. Inhibition was dose-dependent and decreased with the increase of the hormone concentration. SITS did not affect progesterone production in the R.

[The role of eicosanoids and progesterone in the ovulation of the oocytes in the common frog].

Prostaglandin F2 alpha (1-5 micrograms/ml) stimulated ovulation in vitro of Rana temporaria oocytes in the absence of pituitary suspension and potentiated the effects of progesterone. The inhibitor of cyclooxygenase indomethacin (0.01-10 micrograms/ml) decreased the rate of oocyte ovulation stimulated by the pituitary suspension.

[The effect of an inhibitor of chloride channels and of media with a decreased concentration of chlorine ions on the ovulation of oocytes in the common frog].

Ovulation of the Rana temporaria oocytes stimulated in vitro by the suspension of homologous pituitaries is suppressed by the chloride channel inhibitor SITS and media with reduced concentration of chloride ions. SITS and media with reduced concentration of chloride ions do not affect the progesterone-stimulated ovulation of oocytes. The mechanism of stimulating the effect of the gonadotropins on ovulation of the amphibian oocytes is discussed.

[The effect of a chloride channel inhibitor and of media with a decreased concentration of chlorine ions on spontaneous oocyte maturation in the common frog and the clawed toad].

Chloride-deficient media (irrespective of anions substituted for chloride) increased the rate of spontaneous maturation of follicle-enclosed (FEOs) and denuded oocytes in Rana temporaria and Xenopus laevis. The chloride channel blocker SITS (4-acetamido-4'-isothiocyanostilbene-2,2'-disulphonic acid) (10 microM) significantly decreased the rate of the spontaneous maturation of the FEOs and oocytes. The addition of 10 mM (instead of 2.

[The nuclei of the follicular cells regulate steroidogenesis stimulated by a pituitary suspension in the follicles of the common frog in vitro].

It has already been shown that the follicle cell nuclei are not involved in regulation of amphibian oocyte maturation stimulated by the gonadotropic hormones (Skoblina and Kondrat'eva, 1992). In order to elucidate their involvement in regulation of steroidogenesis, we determined changes in the content of progesterone, testosterone, and estradiol-17beta in the common frog follicles stimulated by the pituitary suspension after preliminary treatment with actinomycin D and without it. Treatment with actinomycin D (5 micrograms/ml) reliably decreased the content of progesterone and increased that of testosterone.

Involvement of cAMP in inhibition of maturation of follicle-enclosed oocytes by actinomycin D in Xenopus laevis and Rana temporaria.

Production of estradiol-17 beta and cAMP was assayed during maturation of the follicle-enclosed oocytes of Xenopus laevis and Rana temporaria stimulated by pituitary suspension or hCG, correspondingly. In some samples, the nuclear function was suppressed by pretreatment with AD. The level of estradiol-17 beta in the oocytes of the both species was very low and was not affected by hormonal or AD treatment, while the level of cAMP (follicle+medium) increased.

[The role of chloride channels and chlorine ions in regulating the in-vitro chorionic gonadotropin-stimulated maturation of oocytes in the clawed toad].

The blocker of chloride channels SITS (4-acetamido-4'-isothiocyanostilbene-2,2'-disulphonic acid) (1 and 10 microM) reliable inhibited maturation of Xenopus laevis oocytes stimulated in vitro by human chorionic gonadotropin (5-40 MU/ml) and decreased the progesterone content of the incubation medium. The effect of SITS was dose-dependent and decreased with the increase of the hormone concentration. When the chloride ions in the medium were substituted for equimolar concentrations of sodium, potassium and calcium glutamates or of sodium or potassium chlorides for, respectively, glutamine and aspartate, the percentage of definitive oocytes (1.