Publications by authors named "Yohkaichiya T"

Activin A, a dimer of the betaA-subunit of inhibin, has been shown to have multiple biological activities and sites of production. Follistatin is a high-affinity binding protein for activin, which neutralizes its activity. This study provides the first data, using a cross-sectional design, on the measurement of both these proteins in the maternal circulation of a large cohort of women (6-39 weeks of gestation, n = 2-20 women/time point) during normal pregnancies, and confirms that similar patterns are seen in nine women studied longitudinally during pregnancy.

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Objective: To determine the maternal serum concentrations of inhibin, E2, P, and hCG in early pregnancies arising from IVF and ET or GIFT and to assess the value of these hormone measurements in determining outcome of pregnancy.

Design: Serum immunoactive inhibin, E2, P, and hCG levels were measured in the first trimester of pregnancies after IVF-ET and GIFT procedures.

Setting: In vitro fertilization and ET or GIFT was undertaken at Monash IVF, Melbourne, Victoria, Australia.

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The possible physiological significance of endogenous inhibin was evaluated in prepubertal female rats during sexual maturation. Ovarian/serum inhibin, serum FSH levels were measured from 4th day to 35th day of life by RIA. Serum inhibin levels were first detected on 4th day of life, thereafter, progressively increasing up to 27th day.

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Objective: To examine the inter-relationships between inhibin, relaxin, steroid concentrations, estradiol (E2), progesterone (P), and gonadotropins in early pregnancy.

Design: Hormone concentrations in plasma were measured during the luteal phase of subjects who became pregnant (n = 58) or failed to become pregnant (n = 47) after ovarian hyperstimulation for in vitro fertilization-gamete intrafallopian transfer (IVF-GIFT) (group 1). A further group of subjects became pregnant (n = 7) or failed to become pregnant (n = 8) during endocrinology tracking of a natural cycle (group 2).

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This study examines the source of inhibin in the maternal circulation of pregnant rats by measuring serum immunoactive inhibin levels following a range of experimental procedures. Ovariectomy at days 7, 13 or 19 of gestation, with maintenance of pregnancy by supplementation with progesterone and oestradiol dipropionate, led to a profound fall of serum inhibin levels in comparison with controls, demonstrating that the ovary is a major source of circulating inhibin. This conclusion was supported by the inhibition of the late rise (days 16-22) in serum inhibin in pregnant rats which were hypophysectomized on day 15 and maintained with oestrogen and progesterone supplementation.

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Serum inhibin levels were measured by heterologous RIA during pregnancy, lactation, and the post-weaning estrous cycle in the rat and correlated with changes in serum FSH and LH and prolactin. Blood was serially collected by cardiac puncture under light ether anesthesia from adult Sprague-Dawley rats on alternate days throughout the experimental period. For the first 8 days of pregnancy, immunoreactive inhibin levels remained high, then gradually decreased to reach a nadir at Day 16, and subsequently rose steeply until parturition.

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Immunoactive inhibin (ir-inhibin) concentrations in maternal serum during normal human pregnancy have been established in two separate studies employing cross-sectional and longitudinal sampling regimes. Ir-inhibin concentrations rose from the mid-luteal phase (geometric mean + 95% confidence intervals 1.490 (1.

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Objective: To define the concentrations of inhibin in serum and tissue of patients with hydatidiform mole and assess their value as a clinical marker of the condition.

Design: Prospective study of new patients with hydatidiform mole, comparison of paired observations, and case-control analysis.

Setting: A university hospital, two large public hospitals, and a private women's clinic in Japan.

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Prolactin in the amniotic fluid is known to have an osmoregulatory function in the fetus, but little is known of the effects prolactin in the exudate from the endometrium acting directly on the early embryo. ICR female mice were stimulated with 6 IU of PMSG (pregnant mare serum gonadotropin) and 8 IU of hCG (human chorionic gonadotropin) and mated with ICR males. Two-cell embryos through blastocysts were obtained for in vitro culture, to which prolactin was added at doses of 0, 10, 30, 100, 300 or 1000 ng/ml.

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Fibronectin has the characteristics of adhesiveness and cell migration promotion which may play important roles in embryo implantation. Using the direct and indirect immunofluorescence techniques, we found fibronectin on the blastocyst, and the trophoblast cells of the egg cylinder stage embryo, especially at the sites of cell spreading, as well as the inner cell mass. The results show that (i) fibronectin is used for the initial cell attachment to the plastic dish, and (ii) during the course of embryo growth in vitro, the trophoblast cells spread over the plastic dish in the area of cells which contain many granules of fibronectin.

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Among the characters of fibronectin, the adhesiveness may play an important role in embryo implantation. It is concluded that, using the direct and indirect immunofluorescence techniques, fibronectin was not found on the zona pellucida, but on the embryo surface even from the two cell stage. The results imply that (i) fibronectin is not an initial differentiation marker for the stage of endoderm, which used to be postulated, (ii) the surface fibronectin which has been produced at least from the two cell stage is covered by the zona pellucida to mask its adhesiveness during the oviduct transport, and (iii) after hatching in the uterus cavity the surface fibronectin facilitates the embryo implantation.

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In order to study the morphological features of mouse embryos in the early developmental stage, we first established an in vitro culture system applying a collagen gel layer, and then observed the morphology of the embryos cultured in this system. Embryos after hatching were attached to the collagen gel layer and grew to the egg cylinder stage. By means of morphological analysis of embryos cultured for 3 or 4 days, some interesting characteristics, such as processes and villi of the mural trophoblast, lacunae formation in the mural trophoblast, steroid synthesis of the mural and polar trophoblasts and desmosome or intermediate junctions between the mural and the polar trophoblasts, were revealed.

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Cell junctions in mouse blastocyst were ultrastructurally investigated with or without lanthanum tracer. Tight junctions, gap junctions and desmosomes were observed in the trophectoderm. The tight junction was located near the zona pellucida in all trophoblast interspaces, whereas the gap junction and the desmosome, which were infrequently observed, were localized far from the zona pellucida.

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We have evaluated serum estradiol, progesterone, testosterone, and urinary estrogen excretion in 24 hour urine samples to monitor indices of follicular maturation. The serum steroid levels were determined with the direct radioimmunoassay kit. The urinary estrogen level was measured with the estrogen micrometering kit using hemagglutination inhibition reaction.

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The experiments were performed in order to reveal the role of prostaglandins in the implantation process, using indomethacin, a inhibitor of prostaglandin synthesis. Indomethacin was administered to mice on various days of pregnancy, and then the number of implantation sites and the uterine weight per the number of implantation sites were determined on day 10 of pregnancy. Furthermore [3H]uridine incorporation of blastocysts incubated in the medium containing indomethacin with/without prostaglandin F2 alpha was evaluated in vitro.

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Mouse blastocysts collected on day 4 were cultured for 20 hours in media containing various concentrations of [3H]estradiol with/without 10(-6) M unlabelled estradiol. There was a significant reduction in the radioactivity of embryos cultured at 4 degrees C compared with that of embryos cultured at 37 degrees C. The radioactivity of embryos kept in the washing solution after washing was slight lower but showed no significant difference when it was compared with that of embryos not kept in this way.

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