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At least 199 records · Page 11Linked to original sources
PubMed1998

An unexpected triplet heterotopic pregnancy after replacement of two embryos.

We report a case of a triplet heterotopic pregnancy consisting of an intrauterine monozygous twin pregnancy and a tubal pregnancy after replacement of only two embryos in an in-vitro fertilization cycle with donor spermatozoa. This case demonstrates that sonographic demonstration of two intrauterine pregnancies after transfer of two embryos does not exclude the presence of an ectopic pregnancy. As both heterotopic pregnancy and spontaneous monozygotic twinning are more frequent after the use of assisted reproductive techniques, this combination, although extremely rare, must be kept in mind, especially in older patients with pre-existing tubal damage.

Adult↗
PubMed1999

Reduced survival after human embryo biopsy and subsequent cryopreservation.

Preimplantation genetic diagnosis (PGD) is performed in couples at risk of genetic disease, so as to avoid transfer of embryos which are affected by a monogenic disease or which carry chromosomal aberrations. As in all in-vitro fertilization (IVF) cycles, supernumerary non-affected good-quality embryos may be available after PGD. These embryos can be cryopreserved. So far, limited data on survival after cryopreservation of biopsied human embryos are available. In this study, human embryos of good morphological quality derived from abnormal fertilization were used to evaluate the influence of the embryo biopsy procedure on survival after cryopreservation. Embryos were allocated to three different groups: control (n = 20), drilling-only (n = 16), and biopsy (n = 29). After freezing and thawing, a significantly lower number of blastomeres was intact in the drilling-only group (46/118, i.e. 39.0%, P < 0.01) and in the embryo biopsy group (46/156, i.e. 29.5%, P < 0.0001) than in the control group (85/151, i.e. 56.3%). This difference was reflected in survival rates of embryos. Fifty-five per cent of the control embryos, 37.5% of the drilling-only group, and 33.3% of the biopsy group had at least 50% of their blastomeres intact. After further in-vitro culture, four blastocysts, three from the drilling-only group and one from the biopsy group, developed from the surviving embryos. From this study it can be concluded that current cryopreservation procedures are less successful when biopsied human embryos are cryopreserved, but that surviving embryos can develop to the blastocyst stage and thus may have the potential to develop to term.

Biopsy↗
PubMed1990

Assessment of the viability and pregnancy potential of mouse embryos biopsied at different preimplantation stages of development.

The developmental potential in vitro and in vivo of preimplantation mouse embryos biopsied at the 4-cell, 8-cell and morula stages were investigated. Biopsy had the least impact when performed at the 8-cell stage. There was no effect of biopsy on the development of 8-cells of blastocysts in vitro (95% compared with 99% of controls) or the implantation rate after transfers (82 versus 87%, P greater than 0.05); however, fewer embryos (52 versus 71%, P less than 0.05) resulted in viable fetuses. There was no effect of biopsy at the 8-cell stage on fetal weight on day 17. Blastocyst formation in vitro was significantly less for 4-cell biopsies compared with their controls (76 versus 90%, P less than 0.001) and biopsy also affected the implantation rate (44 versus 59%, P less than 0.01). Biopsy was most detrimental when performed on morulae, reducing the implantation rate from 65% for controls to 21% for biopsies (P less than 0.001). Fetal viability was also markedly affected with a reduction on day 17 from 42 to 26% accompanied by a significant reduction (24%, P = 0.02) of the mean fetal weight. Handling of embryos for biopsy at the morula stage, which involved removal of the zona pellucida, was a significant but not complete cause of the reduced implantation potential observed (sham-controls and intact-controls: 34 and 65%, P less than 0.001), while puncture of the zona during the biopsy of 4-cell and 8-cell embryos had no effect. Therefore, the 8-cell mouse embryo is the most suitable state for embryo biopsy.

Animals↗
PubMed1992

Incidence and significance of unequal gestational sac diameter or embryo crown-rump length in twin pregnancy.

The incidence of differences in gestational sac diameter and crown-rump length, measured at the time of the first ultrasound, in which at least one gestational sac or crown-rump length could be visualized, were analysed retrospectively in 260 twin pregnancies in which one or both fetuses were delivered at term. The difference in gestational sac diameter averaged 1.2 +/- 0.1 mm for pregnancies which ended in twin births, compared to 2.0 +/- 0.3 mm when pregnancy ended in single births (P less than 0.02). The difference in crown-rump length averaged 2.4 +/- 0.6 mm for pregnancies which ended in a single birth, compared to 0.9 +/- 0.1 mm for twin births (P = 0.02). Disparities of greater than or equal to 3 mm in gestational sac diameter (P less than 0.05) or crown-rump length (P less than 0.001) were associated with an embryo loss rate greater than or equal to 50%. The disparity in gestational sac diameter (P less than 0.04) and crown-rump length (P less than 0.01) was smaller in pregnancies resulting from assisted reproductive technologies, compared with pregnancies resulting from coitus or insemination. Differences in gestational sac diameter and crown-rump length in early pregnancy were unrelated to differences in birth weight, length or sex.

Extraembryonic Membranes↗
PubMed2004

Uterine androgen receptors: roles in estrogen-mediated gene expressionand DNA synthesis.

The localization of androgen receptors (AR) and their ligands in the uterine microenvironment at early pregnancy suggest a role for AR in uterine physiology. We have evaluated AR expression in the pig uterine endometrium and examined whether AR ligands modulate peri-implantation uterine gene expression. Northern blot analysis demonstrated the approximately 10.5 kilobase AR transcript in endometrium. Endometrial levels of AR mRNA and protein were greater at early than at mid- or late pregnancy. Estrogen receptor-alpha mRNA levels showed similar maximal expression at early pregnancy. Immunocytochemical analysis of endometrium at early pregnancy localized AR to nuclei of glandular epithelial (GE) and stromal (ST) cells. To evaluate a role for AR in uterine gene regulation, the levels of mRNAs for insulin-like growth factor-I (IGF-I), proliferative cell nuclear antigen (PCNA), and AR itself were assessed in uterine endometrial explant cultures treated with estradiol-17beta (E), testosterone (T), and 19-nortestosterone (N). Induction by E of AR mRNA abundance occurred in endometrium from Day 10 but not from Day 12 pregnant animals and this was partially blocked by coaddition of N or T, although neither androgen alone had any effect. Abundance of IGF-I and PCNA mRNAs was increased by E and inhibited by coaddition of either T or N in Day 10 pregnant pig endometrium. In endometrium from Day 12 pregnant animals, addition of either N or T with E increased IGF-I mRNA levels over that of controls, although E alone was without effect. In contrast, PCNA mRNA abundance was suppressed by all steroid treatments in these explants. DNA synthesis in primary cultures of GE cells from endometrium at Days 10 and 12 of pregnancy was increased by E and was suppressed by T, the latter only at Day 12. E did not affect DNA synthesis in ST cells from endometrium at either pregnancy day, although T inhibited this process in an E-dependent manner in ST cells from pregnancy Day 12. Results identify AR in the pig endometrium during the window of maternal receptivity for implantation and demonstrate the functional, albeit complex, interactions of androgens and estrogens in the regulation of uterine endometrial gene expression and cell growth in vitro. Further elucidation of the role of androgens and their receptor in early pregnancy events may be relevant to an understanding of peri-implantation embryo loss.

Androgens↗
PubMed2000

In vivo and in vitro impairment of human and ram sperm nuclear chromatin integrity by sexually transmitted Ureaplasma urealyticum infection.

The incidence of Ureaplasma urealyticum infection in the semen of infertile men is variable (7%-42%). Evidence has accumulated through routine semen analysis to suggest that this infection can cause embryo loss without necessarily affecting sperm quality. The aim of this study was to specifically investigate the effects of U. urealyticum infection on sperm chromatin stability and DNA integrity, which are known to be correlated to pregnancy outcome. Sperm cells isolated from human semen infected in vivo with U. urealyticum exhibited a low percentage of stable chromatin as determined by nuclear chromatin decondensation assay (42% +/- 4.8%, n = 8) and a high percent of denatured DNA as determined by sperm chromatin structure assay (60.9% +/- 9.1%, n = 7). After doxycyclin treatment, a significant improvement in both parameters was observed (73.7% +/- 3.6%, P: < 0.001 and 30.1% +/- 3.5%, P: < 0.008, respectively). Sperm cells infected in vitro exhibited higher rates of viability and motility than uninfected cells. In contradistinction, U. urealyticum caused significant dose- and time-dependent chromatin decondensation and DNA damage. The percentage of human sperm cells with denatured DNA increased significantly by 54.9% +/- 23.9% and 47. 9% +/- 12.1%, after 30 min infection with serotypes 8 and 3, respectively, at a multiplicity of infection of 100 ureaplasmas per sperm compared with uninfected control cells. The damage to DNA was significantly more pronounced in infected ram sperm (180.9% +/- 21. 5%). These results indicate that preserved sperm activity post U. urealyticum infection resulted in damage to paternal DNA, although a high fertilization rate was maintained, and embryonic development may, therefore, be impaired.

Animals↗
PubMed2002

In vivo effect of leukemia inhibitory factor (LIF) and an anti-LIF polyclonal antibody on murine embryo and fetal development following exposure at the time of transcervical blastocyst transfer.

Leukemia inhibitory factor (LIF) enhances in vitro murine preimplantation development in a time- and dose-dependent fashion. Knockout experiments have demonstrated that endometrial LIF is essential for in vivo murine implantation. We assessed the impact of LIF and an anti-LIF polyclonal antibody (pab) on in vivo development and developed a novel and successful nonsurgical method of embryo transfer for this species, a transcervical blastocyst transfer technique. The objectives of this study were to evaluate the effects of LIF and the anti-LIF pab on 1) implantation, resorption, pregnancy, and viability rates and 2) the overall structural and skeletal development. Two-cell embryos were recovered from superovulated mated donors, cultured to the expanded blastocyst stage, and transferred transcervically into pseudopregnant recipients. Exposure to 5000 U/ml LIF resulted in significant increases in implantation, pregnancy, and viability rates compared with controls. A similar dose of pab produced overall inhibitory effects with a significant decrease in implantation rate. Paradoxically, lower pab doses resulted in significantly increased viability rates. Exposure to LIF had no effect on fetoplacental development. However, pab treatments had variable but significant negative effects on placental length, ossification of the exoccipital bone, and vertebral space width compared with controls. Exposure of murine blastocysts to LIF at the time of transcervical transfer resulted in pronounced positive effects on implantation and pregnancy rates without affecting fetal development. A similar pab dose dramatically reduced implantation and pregnancy rates; at high and low doses, pab produced deleterious effects on placental and skeletal development.

Animals↗
PubMed1988

Evidence that specific cellular immunity cannot account for death of Mus caroli embryos transferred to Mus musculus with severe combined immune deficiency disease.

Mus caroli blastocysts transferred to pseudopregnant Mus musculus implant but die about midgestation. Death of the M caroli embryos is associated with infiltration of the fetoplacental units by M musculus lymphocytes, including functional cytotoxic T lymphocytes (CTL). To determine if specific maternal antifetal immune responses are responsible for the initiation of M caroli failure, survival of M caroli embryos transferred to M musculus with severe combined immune deficiency disease (SCID) was studied. C.B.-17 scid mice, homozygous for the scid gene, are reported to be unresponsive to T cell or B cell mitogens and to alloantigens. We have evaluated responses of C.B.-17 scid mice to M caroli xenoantigens in vivo and in vitro. C.B.-17 scid fail to reject M caroli skin grafts, and their spleen cells do not proliferate when mixed with M caroli splenocytes in a 1-way mixed leukocyte culture. Further, neither primary nor secondary challenge of C.B.-17 scid footpads with M caroli splenocytes elicits a delayed-type hypersensitivity (DTH) response. These results suggest that C.B.-17 scid mice are unable to recognize or respond specifically to M caroli xenoantigens. M caroli embryos transferred to C.B.-17 scid mice implant but fail to survive while cotransferred M musculus embryos are normal. Histologic examination of resorbing embryos revealed granulocytes, macrophages, large granular lymphocytes, but very few small lymphocytes at the implantation sites. Thus, it appears that specific maternal antifetal immune responses are not responsible for initiation of M caroli embryo failure in the M musculus uterus. These studies also indicate that efficient resorption of embryos does not require the function of T cells or B cells.

Animals↗
PubMed1998

Prenatal bias in sex ratios in a marsupial, Antechinus agilis.

Biased sex ratios of young of birds and mammals clearly occur and may have an adaptive significance, but we rarely know the stage at which a bias is generated, or the mechanism. If a bias is generated prior to birth, studies of marsupials may be insightful because gestation is short and neonates are relatively undifferentiated. This study investigated whether biased sex ratios in Antechinus agilis are generated in the brief period between birth and the attachment of young to the mother's teats. When all young born, or just pouch young, or supernumerary young were considered, litters were strongly biased towards females (0.32 males), and there was no significant difference across the groups, so a bias is generated before birth in this species. Evidence from counts of corpora lutea suggests that embryo loss during gestation cannot account fully for the level of bias observed. Therefore, prefertilization mechanisms must contribute to the generation of sex-biased litters in this marsupial.

Animals↗
PubMed2005

Successful sons or superior daughters: sex-ratio variation in springbok.

Mothers would often benefit from producing more offspring of one sex than the other. Although some species show an astonishing ability to skew their sex ratio adaptively, the trends found in many studies on vertebrates have proved inconsistent. Furthermore, evidence for a mechanism by which such a bias is achieved is equivocal at best. Here, we examine sex-ratio variation over 30 years, both at an individual and a population level, in the highly polygynous, size-dimorphic springbok (Antidorcas marsupialis). Many previous studies of similar species have shown that mothers in superior condition preferentially produce sons, whereas those in poorer condition produce more daughters. We found the opposite to be true in springbok, perhaps because daughters provide mothers in superior condition with a more rapid and secure fitness return. This theory was supported by the findings that earlier-conceived offspring tended to be female and that an increased proportion of daughters were produced with increasing rainfall (which was likely to reduce nutritional stress). We also show that selective reabsorption of embryos is unlikely to be the main mechanism by which deviations from an equal sex ratio are achieved. Hence, either differential implantation occurs or females are able to influence the sex of the sperm fertilizing an egg.

Age Factors↗
PubMed2005

Heart induction by Wnt antagonists depends on the homeodomain transcription factor Hex.

Inhibition of canonical Wnt/beta-catenin signaling by Dickkopf-1 (Dkk-1) or Crescent initiates cardiogenesis in vertebrate embryos. However, nearly nothing is known about the downstream effectors of these secreted Wnt antagonists or the mechanism by which they activate heart formation. Here we show that Wnt antagonists in Xenopus stimulate cardiogenesis non-cell-autonomously, up to several cells away from those in which canonical Wnt/beta-catenin signaling is blocked, indicative of an indirect role in heart induction. A screen for downstream mediators revealed that Dkk-1 and other inhibitors of the canonical Wnt pathway induce the homeodomain transcription factor Hex, which is normally expressed in endoderm underlying the presumptive cardiac mesoderm in amphibian, bird, and mammalian embryos. Loss of Hex function blocks both endogenous heart development and ectopic heart induction by Dkk-1. As with the canonical Wnt pathway antagonists, ectopic Hex induces expression of cardiac markers non-cell-autonomously. Thus, to initiate cardiogenesis, Wnt antagonists act on endoderm to up-regulate Hex, which, in turn, controls production of a diffusible heart-inducing factor. This novel function for Hex suggests an etiology for the cardiac malformations in Hex mutant mice and will make possible the isolation of factors that induce heart directly in the mesoderm.

Animals↗
PubMed2004

Distribution of the lipolysis stimulated receptor in adult and embryonic murine tissues and lethality of LSR-/- embryos at 12.5 to 14.5 days of gestation.

The lipolysis stimulated receptor (LSR) recognizes apolipoprotein B/E-containing lipoproteins in the presence of free fatty acids, and is thought to be involved in the clearance of triglyceride-rich lipoproteins (TRL). The distribution of LSR in mice was studied by Northern blots, quantitative PCR and immunofluorescence. In the adult, LSR mRNA was detectable in all tissues tested except muscle and heart, and was abundant in liver, lung, intestine, kidney, ovaries and testes. During embryogenesis, LSR mRNA was detectable at 7.5 days post-coitum (E7) and increased up to E17 in parallel to prothrombin, a liver marker. In adult liver, immunofluorescence experiments showed a staining at the periphery of hepatocytes as well as in fetal liver at E12 and E15. These results are in agreement with the assumption that LSR is a plasma membrane receptor involved in the clearance of lipoproteins by liver, and suggest a possible role in steroidogenic organs, lung, intestine and kidney). To explore the role of LSR in vivo, the LSR gene was inactivated in 129/Ola ES cells by removing a gene segment containing exons 2-5, and 129/Ola-C57BL/6 mice bearing the deletion were produced. Although heterozygotes appeared normal, LSR homozygotes were not viable, with the exception of three males, while the total progeny of genotyped wild-type and heterozygote pups was 345. Mortality of the homozygote embryos was observed between days 12.5 and 15.5 of gestation, a time at which their liver was much smaller than that of their littermates, indicating that the expression of LSR is critical for liver and embryonic development.

Animals↗
PubMed2004

Effects of interleukin-12 administration during the pre- and peri-implantation period on mouse embryofetal development.

PROBLEM: The immunological success of pregnancy is thought to depend upon the establishment of a balance between favorable and deleterious cytokines, the current paradigm viewing pregnancy as a T helper (Th)2 cytokine-dependent phenomenon. In this context, a particular attention should be directed to the potential role of interleukin (IL)-12, which promotes the development of Th1 responses, in the induction of adverse pregnancy-related phenomena. Indeed, very few data linked the Th1-inducer IL-12 to the event of abortion. METHODS: In this study, we have investigated the maternal and fetal effects of exogenous administration of IL-12 to CD1 (BR) ICR mice during the pre- and peri-implantation period (day 2-6 of pregnancy). Animals have been evaluated for parameters of reproductive performance, embryo and fetal developmental toxicity and maternal toxicity. RESULTS: Intraperitoneal administration of IL-12 at concentrations from 2.5 to 10 microg/kg daily did not result in an increase in the murine abortion rate. A statistically significant, although minimal, decrease in the number of somites were found in the embryos of animals treated with IL-12 at a dose of 10 microg/kg/day. However, developmental parameters at birth were similar between the two groups of animals suggesting that alteration of somites might be a transitory state during treatment. An increased body weight gains and reduced feed and water consumption were observed in the mothers treated with the cytokine. CONCLUSION: In the present experimental conditions and in this specific strain of mice, IL-12 does not exert adverse effects on reproductive performance and induces an only modest harmful action on mothers and embryos.

Abortion, Spontaneous↗
PubMed1980

Ovulation rate at first mating and reproductive performance of gilts.

Laparoscopy was used to estimate ovulation rate at first mating in 460 Large White/Landrace gilts. For 385 gilts which farrowed litter size was recorded and the relationships between age and mating, maternal litter size, ovulation rate and reproductive performance were examined. The mean ovulation rate of the gilts which farrowed was 10.9 +/- 0.14 corpora lutea and the mean first litter size was 8.0 +/- 0.12 piglets born with 7.5 greater than or equal to +/- 0.13 born alive. Ovulation rate was related to first litter size (r = 0.29, P < 0.001) but embryo loss was the major factor determining litter size, accounting for about 58% of the variation. None of the variable examined at the time of mating was sufficiently correlated with litter size to be useful as selection criteria for improving reproductive performance.

Animals↗