[Effects of cycloheximide, aminoglutethimide, indomethacin, cytochalasin B and colchicine on ovulation and the ultrastructure of the ovarian follicle wall in the stellate sturgeon Acipenser stellatus Pall]. / Vliianie tsiklogeksimida, aminogliutetimida, indometatsina, tsitokhalazina B i kolkhitsina na ovuliatsiiu i ul'trastrukturu stenki ovarial'nogo follikula sevriugi Acipenser stellatus Pall.

The inhibitor of protein synthesis cycloheximide, inhibitor of steroidogenesis aminoglutethimide, and inhibitor of prostaglandin synthesis indomethacin, as well as the drugs affecting the cell cytoskeleton, such as cytochalasin B and colchicine, were used for studying the mechanisms of ovulation in the stellate sturgeon Acipenser stellatus Pall. Follicles were isolated from the body cavity within certain time intervals after the injection of pituitary suspension to a female and cultivated in media with the inhibitors. In the case of follicles isolated in the middle of the period from hormonal injection until ovulation, cycloheximide, cytochalasin B, and aminoglutethimide suppressed ovulation most effectively, while in the case of oocytes isolated during the last quarter of this period, aminoglutethimide and cytochalasin B were the most effective. It was shown using TEM and SEM that cycloheximide suppressed all processes related to the preparation for ovulation, except the initial ones: contraction of follicle cells and their processes and secondary flattening of these cells. In the presence of aminoglutethimide, the follicle cells underwent pathological changes. Incubation in the media containing indomethacin and colchicine prevented degradation of the outer theca layer at the follicle apex. In the presence of cytochalasin B affecting the cytoskeleton, the drawing of follicle cell processes from the jelly coat channels was blocked, the outer theca cells were strongly contracted, but the cell layer integrity was affected and it was divided in separate fragments. A relationship is discussed between the metabolic processes and morphological changes that lead to ovulation. It was proposed on the basis of the present and previous data that the preovulatory preparation of the follicle tissues comprises two contractile and two apoptotic processes distinctly coordinated in time and space.

[The action of neurotransmitters and their antagonists on oocyte maturation. The action of serotonin antagonists on the in-vitro maturation of amphibian oocytes]. / Deistvie neirotransmitterov i ikh antagonistov na sozrevanie ootsitov. Deistvie antagonistov serotonina na sozrevanie in vitro ootsitov amfibii.

Serotonin antagonists (inmecarb hydrochloride and inmecarb methiodide) stimulate in vitro maturation of Bufo viridis and Xenopus laevis oocytes or potentiate the action of progesterone. In contrast to that, serotonin inhibits or blocks oocyte maturation stimulated by progesterone or serotonin antagonists. Sensitivity of B. viridis oocytes to serotonin, its agonists and antagonists is subject to seasonal changes. A maximum sensitivity of intact oocytes is observed in February-March, and that of denuded ones in May-June. We suggest that endogenous serotonin is involved in maintenance of the block of meiosis and in the oocyte maturation control in amphibians.

The control of oocyte maturation in the starfish and amphibians by serotonin and its antagonists.

Serotonin acts as antagonist of progesterone on amphibian oocytes. Serotonin antagonists inhibit maturation of starfish oocytes and stimulate or trigger maturation in amphibians. We propose that endogenous serotonin participates in the control of oocyte maturation.

[Chronology of the embryonic development of the common frog]. / Khronologiia zarodyshevogo razvitiia travianoi liagushki.

The tables of embryonic development of the common frog (Dabagyan, Sleptsova, 1975) have been made more precise: more precise timing of successive developmental stages (in the number of tau 0) from fertilization till hatching was provided and new drawings of the embryos during gastrulation were given.