Biomedical subjects

L S Roblero

Publications and source records attributed to L S Roblero.

8 recordsLinked to original sources

PubMed1992

Fertilization rate in couples with unexplained infertility.

A group of 24 couples with unexplained infertility was scheduled for in-vitro fertilization and tubal embryo transfer between May 1989 and September 1990. In the same period, in-vitro fertilization and intrauterine transfer of embryos was planned in a control group of 44 women with tubal infertility. The mean age and duration of infertility were similar in both groups and the same scheme of ovarian stimulation was used. No statistically significant difference was obtained comparing oestradiol levels and numbers of mature oocytes retrieved between the group of patients with unexplained infertility and those with tubal infertility. The fertilization rate of the oocytes obtained from women with unexplained infertility (60.4%) was significantly lower (P less than 0.001) than that of the oocytes obtained from patients with tubal infertility (87.3%). There was no statistically significant difference in the cleavage rates between patients with unexplained infertility and those with tubal infertility. It is concluded that lack of fertilization is an unexplored cause of infertility in couples with unexplained infertility.

Adult↗

PubMed1991

Effect of RU486 on development and implantation of rat embryos.

This study evaluated the effects of postcoital treatment with the antiprogestin RU486 on transport, development and implantation of rat embryos. Doses of 0.1, 0.5, 1.0, 2.0, or 3.0 mg/rat of RU486 were injected subcutaneously on days 1, 1 + 2, or 4 of pregnancy. Autopsies were carried out on days 5 or 12 of pregnancy. RU486 provoked a significant dose-related reduction in the number of recovered embryos and inhibited their development (day 5) and decreased the number and size of implanted embryos (day 12). Treatment on day 4 was the least effective. Blastocysts recovered from RU486-treated rats exhibited comparable rate of trophoblastic outgrowth in vitro as the controls. Blastocysts transferred from RU486-treated rats to synchronous untreated pseudopregnant recipients yielded implanted embryos 12 days later in all recipients, although at a significantly lower rate than the controls. Blastocysts transferred from control pregnant rats to RU486-treated pseudopregnant recipients failed to implant completely when the dose was greater than or equal to 1.0 mg. The interceptive mechanism of postcoital treatment with RU486 in the rat involves loss of embryos from the reproductive tract and altered development prior to implantation. Endometrial receptivity or the ability of the uterus to retain the embryos until the time of implantation are also impaired by RU486. The embryos that survive these effects may experience delayed implantation in their mothers.

Animals↗

PubMed1990

High potassium concentration and the cumulus corona oocyte complex stimulate the fertilizing capacity of human spermatozoa.

Progressively motile spermatozoa were incubated for 24 hours in culture media containing 4.7 or 25 mM K, in the presence or absence of hamster cumulus oophorus. The percentage of spermatozoa with progressive motility was significantly higher at 24 hours in the presence of cumulus corona oocyte complexes, irrespective of K concentration. A significant decrease in sperm mortality was observed with the association of 25 mM K and cumulus cells. A higher percentage of acrosome reaction was observed in spermatozoa incubated in 25 mM K when compared with 4.7 mM K, irrespective of time and the presence or absence of cumulus. The percentage of penetrated oocytes at 2 and 5 hours of incubation was higher when sperm had been incubated in 25 mM K than in 4.7 mM K. The presence of cumulus in the culture medium induced an additional significant increase in the percentage of penetrated oocyte. Although at 24 hours of incubation the percentage of acrosome reaction was higher than at 2 and 5 hours, the percentage of penetrated oocytes did not increase proportionally.

Acrosome↗

PubMed1989

Cumulus cell dispersion induced by estradiol in mouse oviduct in vitro.

Dispersion of cumulus cells in nonmated mice is completed in the oviduct 15-20 h after ovulation. Oviducts, isolated 1 h after ovulation (13 h post-human chorionic gonaditropin), were cultured in vitro for 40 h. In these oviducts, denuded oocytes were first seen at 30 h of culture, indicating that cumulus dispersion proceeded at a slower rate in vitro. Oocyte denudation was accelerated in a dose-dependent manner by the addition of estradiol to the culture medium in which oviducts were incubated. The addition of progesterone or cycloheximide to the culture medium strongly inhibited oocyte denudation even in the presence of estradiol. When isolated cumuli were incubated in the absence of oviductal tissue, the rate of cell dispersion was slower than that of cumuli incubated inside the oviduct and the addition of estradiol to the culture failed to accelerate this process. On the basis of these data, we propose that cumulus cell dispersion is accelerated by an estrogen-dependent protein produced by the oviduct and that this effect of estrogen is antagonized by progesterone.

Animals↗

PubMed1987

The effect of RU486 on transport, development and implantation of mouse embryos.

Pregnancy was interrupted in Swiss-Rockefeller mice by a single subcutaneous injection of the antiprogesterone RU486 given postcoitally. A dose of 0.1 mg/animal injected on day 1, produced partial inhibition of pregnancy, a notable delay in embryonic development and a slight retention of embryos in the oviducts. When the same dose was injected on day 2, 3 or 4, no implantation sites were seen at autopsy performed on day 12 of pregnancy. Treatment with 0.5 or 1 mg/animal on day 1 produced the loss of a large proportion of the embryos from the genital tract by day 4 of pregnancy and suppressed implantation completely. These observations indicate that preimplantation phenomena in mice are highly dependent on progesterone action.

Animals↗

PubMed1986

High potassium concentration improves preimplantation development of mouse embryos in vitro.

Embryo growth in vitro in culture media containing potassium (K) ions at the concentration found in common extracellular fluids proceeds at a slower pace than in vivo. Considering that oviductal fluid has an unusually high concentration of K, the effect of various concentrations of this ion on development of mouse embryos in vitro was investigated. Two-cell to 4-cell preimplantation mouse embryos were cultured in vitro for 47 hours in a medium in which NaCl was partially replaced by KCl at concentrations ranging from 4.7 to 60 mM. The number of cells per embryo increased in a dose-related fashion when the embryos were cultured in the presence of 4.7, 10, and 25 mM of K. Higher K concentrations were detrimental for development. Embryos developed in vitro under different concentrations of K were transferred to pseudopregnant recipient foster mothers as a test of viability. The highest rate of implantation was observed with embryos cultured in medium containing 25 mM K. The results indicate that a high concentration of K in the culture medium (25 mM), comparable to that found in the genital tract of the female mouse, is required for a rate of development in vitro similar to the one observed in vivo.

Animals↗

PubMed1983

Effect of postcoital oestradiol treatment upon transport, growth, differentiation and viability of preimplantation mouse embryos.

This study was designed to assess the relative contribution of ovum transport anomalies and alterations of various developmental parameters upon the contraceptive effect of postcoital estrogen treatment in mice. Females received a single s.c. injection from 0.001 to 100 micrograms of oestradiol or vehicle on day 1 of pregnancy and were sacrificed 28, 52 or 76 hours after treatment to determine the location and development of embryos in the genital tract or on day 12 of pregnancy to assess the number of viable implanted embryos. Preimplantation embryos were classified according to developmental parameters into normal, retarded or arrested. Pregnancy was completely suppressed by 10 and 100 micrograms of oestradiol. A partial and dose related block of pregnancy was observed with 0.01 to 1 microgram of oestradiol. Treatment with these doses was associated with delayed oviductal transport, decreased cleavage rate, inhibition of blastulation and arrested development. The number of implanted embryos recorded on day 12 coincided with the number of normal embryos observed at 76 hours, regardless of their location and number of cells. Statistically significant but minor decreases in the cleavage rate and transitory oviductal retention caused by oestradiol neither prevented implantation nor affected subsequent viability of mouse embryos. It is concluded that the inhibition of pregnancy that follows postcoital administration of oestradiol is associated with a variety of effects upon embryo transport and preimplantation development, which appear in different combinations with each dose and contribute unequally to its interceptive effect.

Animals↗

PubMed1979

Effect of oestradiol-17 beta and progesterone on oviductal transport and early development of mouse embryos.

Transport of embryos through the oviduct, cleavage rate and transformation of morulae to blastocysts, were delayed in females ovariectomized on Day 2 of pregnancy. Oestradiol-17 beta in doses of 60 to 6000 pg/day for 3 days did not normalize the transport of embryos, but the transformation of morulae to blastocysts reached values near or equal to those of the controls, in spite of a lowered rate of cleavage. Progesterone at a dose of 100 micrograms/day, resulted in normal transport, rate of cleavage and rate of differentiation. Treatment with both hormones had synergistic effects on transport and the rate of cleavage and differentiation. These results give further support to the concept that ovarian hormones are the controlling factors for these processes in early pregnancy.

Animals↗