Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Embryos”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17Linked to original sources
PubMed1997

The embryo versus endometrium controversy revisited as it relates to predicting pregnancy outcome in in-vitro fertilization-embryo transfer cycles.

To evaluate embryonic and endometrial factors for their value in predicting pregnancy outcome in in-vitro fertilization (IVF) and embryo transfer, a retrospective data collection and prospective uterine artery colour Doppler imaging study was performed in a university-based IVF-embryo transfer programme setting. A total of 210 patients were included and grouped as follows: (I) IVF with controlled ovarian stimulation (214 cycles); (II) frozen-thaw cycle of autologous embryos (30 cycles); (III) oocyte donation, no cryopreservation (12 cycles); (IV) frozen-thaw cycle with embryos from donated oocytes (10 cycles). Embryo quality was significantly better in pregnant than non-pregnant cycles (group I, P = 0.0104; groups II-IV, P = 0.0418). The endometrial echo was significantly thicker in pregnant versus non-pregnant patients in group I (P = 0.0059), but not in groups II-IV (P = 0.741). Past uterine surgery or abnormalities had no effect on pregnancy outcome. There were no significant differences in mean uterine artery resistance index or peak systolic velocity in pregnant versus non-pregnant patients in groups II-IV. Thus, embryo quality is the most reliable predictor of pregnancy outcome. Endometrial measurements were significantly thicker in subsequently pregnant patients only in group I, where the endometrium reflects the hormonal environment. Doppler parameters were not useful in predicting pregnancy outcome.

Arteries↗
PubMed1997

Succinate and malate improve development of hamster eight-cell embryos in vitro: confirmation of viability by embryo transfer.

The in vitro development of hamster preimplantation embryos is supported by non-glucose energy substrates. To investigate the importance of embryonic metabolism, influence of succinate and malate on the development of hamster 8-cell embryos to blastocysts was examined using a chemically defined protein-free modified hamster embryo culture medium-2 (HECM-2m). There was a dose-dependent influence of succinate on blastocyst development; 0.5 mM succinate was optimal (85.1% +/- 3.9 vs. 54.5% +/- 3.5). In succinate-supplemented HECM-2m, blastocyst development was reduced by omission of lactate (68.5% +/- 7.2), but not pyruvate (85.8% +/- 6.2) or glutamine (84.1% +/- 2.1). Succinate along with either glutamine or lactate or pyruvate poorly supported blastocyst development (28%-58%). Malate also stimulated blastocyst development; 0.01 mM malate was optimal (86.3% +/- 2.8). Supplementation of both succinate and malate to HECM-2m supported maximal (100%) blastocyst development, which was inhibited 4-fold by the addition of glucose/phosphate. The mean cell numbers (MCN) of blastocysts cultured in succinate-supplemented HECM-2m was higher (28.3 +/- 1.1) than it was for those cultured in the absence of glutamine or pyruvate (range 20-24). The MCN was the highest (33.4 +/- 1.6) for blastocysts cultured in succinate-malate-supplemented HECM-2m followed by those in succinate (28.3 +/- 1.1) or malate (24.7 +/- 0.5) supplemented HECM-2m. Embryo transfer experiments showed that 29.8% (+/- 4.5) of transferred blastocysts cultured in succinate-malate-supplemented HECM-2m produced live births, similar (P > 0.1) to the control transfers of freshly recovered 8-cells (33.5% +/- 2.0) or blastocysts (28.9% +/- 3.0). These data show that supplementation of succinate and malate to HECM-2m supports 100% development of hamster 8-cell embryos to high quality viable blastocysts and that non-glucose oxidizable energy substrates are the most preferred components in hamster embryo culture medium.

Animals↗
PubMed2003

Whole-embryo culture of E5.5 mouse embryos: development to the gastrulation stage.

This study reports establishment of an in vitro culture system for E5.5 mouse embryos that supports development to the gastrulation stage and allows the use of experimental approaches to study gastrulation during mouse embryogenesis. Recent experiments suggest that the extraembryonic tissues may play a critical role for gastrulation from as early as E5.5. To apply whole embryo culture to E5.5 embryos and analyze gastrulation, it is essential to optimize the conditions so that most of the embryos develop to the gastrulation stage in culture. For this purpose, we established a protocol in which embryos were isolated using micromanipulator and cultured with 50-75% rat serum. Although cultured embryos tended to grow a larger extraembryonic portion, more than 80% of them developed the primitive streak and induce mesoderm, which corresponds to the mid-streak stage.

Animals↗
PubMed2003

Tetraploid embryos rescue the early defects of tw5/tw5 mouse embryos.

tclw5 is a t-complex recessive lethal mutation of the tw5-haplotype. Since tw5/tw5 embryos die soon after implantation, the tclw5 gene is thought to play an important role in early embryogenesis. Previous histological studies have demonstrated that tw5 homozygotes do not survive past the gastrulation stage due to extensive death of the embryonic ectoderm, whereas the extraembryonic tissues were less affected. In the present study, we demonstrate that tw5/tw5 embryos may be distinguished from wildtype littermates at embryonic (E) day 5.5. At this stage, the visceral endoderm of tw5/tw5 embryos appeared to be different, possessing smaller and fewer vacuoles compared to normal littermates. This led us to hypothesize that the visceral endoderm may be affected by tclw5. Confirmation was provided by the rescue of tw5/tw5 embryos following aggregation with tetraploid embryos. However, rescued embryos did not survive past E9.0 and displayed an underdeveloped posterior region. This would indicate that the actions of tclw5 extend beyond the midgestation stage.

Animals↗
PubMed1995

Freezing of zona-free mouse embryos: characteristics of the plasma membrane and subsequent development of the embryos.

Frozen-thawed mouse embryos with (+ZP) and without (-ZP) zona pellucida have been studied at the Scanning Electron Microscope (SEM) to determine how the process affects the plasma membrane and the subsequent embryo development. The main difference observed in -ZP embryos immediately after thawing is the abnormal morphology and distribution of microvilli. This could explain the spontaneous separation of blastomeres in -ZP embryos, and the decrease in their survival rate. If thawed -ZP embryos are allowed to recover in culture, their plasma membrane characteristics and survival rate are identical to those of control embryos.

Animals↗
PubMed2007

Influence of in vitro oxygen concentrations on preimplantation embryo development, gene expression and production of Hanwoo calves following embryo transfer.

This study evaluated the effects of two different oxygen (O2) concentrations on in vitro embryo development, embryo quality, and gene expression and the in vivo development following embryos transfer to recipients of natural and synchronized estrus in bovines. Cumulus oocyte complexes were in vitro matured in TCM199 supplemented with FSH (10 microg/ml), LH (10 microg/ml), and 10% (v/v) FBS. Presumptive zygotes were cultured in SOF medium either under 5% (low) or 20% (high) O2 in air. Cleavage rates did not differ between groups. Blastocyst and hatched blastocyst development in 5% O2 were significantly (P < 0.05) higher than in 20% O2. Total cell number of in vivo blastocyst was significantly (P < 0.05) higher than that of in vitro blastocyst. ICM ratio and apoptosis of in vivo blastocyst were significantly (P < 0.05) lower than that of in vitro blastocyst. Using real time PCR, we have found that for the set of genes (GLUT-1, MnSOD, VEGF, Bax, and Bcl-2) analyzed, there were differences in mRNA expression between in vitro produced (IVP) and in vivo produced embryos. Interestingly, the abundance of transcript for IFN-tau in IVP embryos produced under 5% O2 concentration was similar to in vivo counterparts. The pregnancy and twin rates of natural recipients were significantly (P < 0.05) higher than those of synchronized counterparts. No significant difference in the offspring sex was observed. In conclusion, low (5%) O2 concentration during IVC was beneficial for enhancing the embryo quality and recipients of natural estrus were more suitable than synchronized estrus for stable production of Hanwoo calves.

Animals↗
PubMed2007

Temporal expression of transcripts related to embryo quality in bovine embryos cultured from the two-cell to blastocyst stage in vitro or in vivo.

The post-fertilization embryo culture environment can have a dramatic effect on the pattern of gene expression in the embryo and it is widely acknowledged that bovine embryos derived from in vitro culture are of inferior quality to those derived in vivo. The objective of this study was to examine temporal variation in the mRNA abundance of several transcription and translation factors known to differ between blastocysts produced following culture in vitro and in vivo. Embryos were recovered from two in vitro culture systems SOF1 or SOF2 at five developmental stages: 2- to 4-cell, 8-cell, 16-cell, morula, and blastocyst. In vivo embryos were produced from superovulated and artificially inseminated heifers and recovered at approximately 40 hr or 3, 4, 5, and 7 days postinsemination. Blastocysts were also produced following in vitro maturation, in vitro fertilization and culture in the ewe oviduct. Analysis of relative transcript abundance for FOXO3A, EEF1G, HMG2, and REA was performed using quantitative real-time PCR. Irrespective of culture environment each transcript followed, approximately the same general pattern of expression where relative abundance decreased dramatically from the 2- to 4-cell stage to 8-cell stage and increased from the morula to blastocyst stage (P < 0.05). Transcripts for GNBL2 were not observed between the 2- and 16-cell stage of development. Relatively high expression at the 2- to 4-cell indicated that these transcripts are most likely of maternal origin produced in the oocyte during growth and final maturation. A culture-induced change in mRNA abundance of transcription and translation factors was evident in embryos that were produced not only between in vivo and in vitro culture environments but also between different in vitro culture systems.

Animals↗
PubMed1996

Outcome of frozen embryo replacement cycles following elective cryopreservation of all embryos in women at risk of developing ovarian hyperstimulation syndrome.

AIM: Our aim was to compare the outcome in subsequent frozen embryo replacement cycles in four groups of patients who had elective cryopreservation of all their embryos because they were considered to be at increased risk of developing severe ovarian hyperstimulation syndrome. DESIGN: Sixty-two (91%) of 68 IVF cycles (68 patients) in which elective cryopreservation of all embryos was performed were analyzed. All patients continued on the GnRH agonist, buserelin, after oocyte recovery until the onset of vaginal bleeding. Frozen embryo replacement occurred in a hormone replacement cycle that started either on day 3 of the withdrawal bleed (group I; N = 15) or after serum estradiol levels had fallen to < 100 pmol/L (group II; N = 16). The other patients commenced a frozen embryo replacement cycle several months later in either a hormone replacement (group III; N = 15) or a natural (group IV; N = 16) cycle. RESULTS: Two patients developed severe ovarian hyperstimulation syndrome. There were no significant differences among the four groups regarding demographic variables, the dose of hMG used, and the clinical outcome. There was a higher but not significantly different clinical pregnancy rate in group I (26.7%), compared to group II (12.5%), group III (13.3%), and group IV (18.8%). CONCLUSIONS: Several options exist for the timing and protocol used for frozen embryo replacement in patients who had elective cryopreservation for the prevention of ovarian hyperstimulation syndrome, none of which was found to be clearly superior in this observational report.

Adult↗
PubMed2000

Co-culture of early embryo with human decidual stromal cells in vitro by improvement of early embryo development.

An early embryo co-culture system with human decidual stromal cells was established to study its effect on early embryonic cleavage and growth in vitro. Three hundred and eight 2-cell mouse embryos were co-cultured with human decidual stromal cell monolayer in MEM + 0.4% bovine serum albumin (BSA) and 163 embryos cultured in MEM + 15% FCS alone as control. Among the mouse 2-cell embryos co-cultured with human decidual stromal cells, 72.73% developed to the morula stage and 67.21% cavitated to blastocysts with 59.74% hatching, as compared with 61.34% to morula stage, 48.47% to blastocysts and none hatching in the controls, respectively. Co-cultured embryos cleaved slightly faster than controls and showed no or less fragmentation than those in the control. These results suggested that human decidual stromal cells can support early embryonic development and yield a reasonable number of embryos with good quality up to blastocyst stage.

Adult↗
PubMed2005

Development of porcine embryos in vivo and in vitro; evidence for embryo 'cross talk' in vitro.

The in vitro development of zygotes of domestic species to the blastocyst stage is facilitated by culture in groups, suggesting a role for autocrine/paracrine factors. A novel method was used to investigate the potential role of such factors using in-vitro-produced and in-vivo-derived porcine embryos. The development of individual zygotes to the blastocyst stage was optimal when they were cultured 81-160 mum apart. As the distance between the embryos was increased, blastocyst rates declined significantly, reaching zero beyond 640 mum. Blastocyst volume and cell number (both inner cell mass and trophectoderm) were also increased when the distance apart was between 81 and 160 mum. Culturing embryos in groups at different stages of development suggested that group culture confers a greater advantage to development after the activation of the genome. Group culture of in-vivo-derived embryos showed a weak distance effect. The results suggest a role for as yet unknown diffusible paracrine/autocrine factors released by early porcine embryos in promoting the growth of neighbouring embryos in vitro. This advantage is observed to a lesser extent by in-vivo-derived zygotes which are likely to have been better conditioned for development in vitro by being conceived in the female reproductive tract.

Analysis of Variance↗
PubMed1985

Embryo toxicity of clomiphene citrate on mouse embryos fertilized in vitro and in vivo.

The effect of the ovulatory agent clomiphene citrate on fertilization and early embryogenesis was investigated with the use of in vitro fertilized mouse oocytes. Alterations in early embryogenesis with clomiphene citrate exposure were further studied with the use of embryos obtained from mouse oocytes fertilized in vivo. In the nontreated group, the fertilization rate was 81%, and 61% of the oocytes reached the blastocyst stage by 96 hours. Both fertilization and blastocyst formation declined in a dose-dependent fashion when clomiphene citrate was added to the culture media in concentrations greater than or equal to 10 micrograms/ml (p less than 0.001). The rate of progressive embryo cleavage was also slower at 48 and 72 hours after drug exposure. Mouse embryos fertilized in vivo demonstrated similar findings, with decreased blastocyst formation and increased degeneration rates, again at clomiphene citrate concentrations greater than or equal to 10 micrograms/ml (p less than 0.01). Exposure to the drug beyond 24 hours had no additional effect. It appears that clomiphene citrate-exposed embryos may undergo subtle changes that later manifest themselves in the form of decreased embryo growth rates and increased embryo degeneration rates.

Animals↗
PubMed1996

Comparison of intravenous albumin and transfer of fresh embryos with cryopreservation of all embryos for subsequent transfer in prevention of ovarian hyperstimulation syndrome.

OBJECTIVE: To compare the efficacy of administration i.v. albumin to prevent severe ovarian hyperstimulation syndrome (OHSS) in patients undergoing ovarian stimulation for IVF with a standard policy of cryopreserving all embryos and to assess the impact of the two methods of treatment on pregnancy rates (PRs). DESIGN: Prospective randomized study. SETTING: A tertiary referral center for assisted conception. PATIENTS: Twenty-six patients undergoing IVF treatment cycles who were considered to be at high risk of developing severe OHSS on the basis of their serum E2 concentrations on the day of hCG administration and the number of oocytes collected. INTERVENTION: In group 1 (n = 13) all the generated embryos were cryopreserved to be transferred subsequently in hormonally manipulated cycles. In group 2 (n = 13) patients received IV infusions of albumin on the day of oocyte retrieval and 5 days later. Patients in group 2 had transfers of fresh embryos. MAIN OUTCOME MEASURES: The total dosage of hMG used, total number of follicles developed, number of follicles > 14 mm in diameter, serum E2 concentrations and endometrial thickness on day of hCG administration, number of oocytes retrieved, number and quality of embryos generated, PRs per cycle commenced, and onset and degree of any OHSS developed. RESULTS: There were no significant differences in the above parameters between the two groups, except for PRs that were significantly higher in patients who had all embryos cryopreserved (38.6% versus 0%). CONCLUSION: The policy of cryopreserving all generated embryos appears as effective as the administration of i.v. albumin in preventing OHSS in high-risk patients and produces significantly higher PRs.

Adult↗
PubMed2003

Developmental competence and post-thaw survivability of buffalo embryos produced in vitro: effect of growth factors in oocyte maturation medium and of embryo culture system.

The present study was conducted to examine the effects of supplementation to IVM medium of epidermal growth factor (EGF), fibroblast growth factor (FGF) and vasoactive intestinal peptide (VIP) along with pregnant mare serum gonadotrophin (PMSG) on oocyte maturation and cleavage of buffalo embryos (experiment 1). The developmental competence of cleaved embryos cultured in either a complex co-culture system (TCM-199+10% serum+oviduct cell monolayer) or defined media (a) modified form of synthetic oviductal fluid (mSOF) was evaluated (experiment 2). The post-thaw morphology and survivability of frozen blastocysts developed from embryos cultured either in complex or defined medium was compared (experiment 3). Aspirated oocytes were cultured in maturation medium (TCM-199+PMSG (40 IU/ml-control)) supplemented with EGF (20 ng/ml), FGF (20 ng/ml) and VIP (20 ng/ml), either alone or in combination, in a CO(2) incubator at 38.5 degrees C for 24h. Maturation rate was assessed and oocytes were inseminated in vitro with frozen-thawed sperm processed in Brackett and Oliphant (BO) medium. The cleaved embryos were cultured either in complex co-culture system or mSOF. Results suggested that EGF had more beneficial effect on buffalo oocyte maturation, and embryo cleavage than FGF. Addition of VIP to the oocyte maturation medium did not improve the results. Blastocyst yields from buffalo oocytes were significantly higher in a complex co-culture system than in defined media (mSOF) when oocytes were matured in presence of EGF either alone or in combination with FGF and VIP. The mean percent of morphologically normal blastocysts after thawing and their survivability were significantly higher in blastocysts obtained from embryos cultured in mSOF than those cultured in complex co-culture system.

Animals↗
PubMed2003

A prospective randomized multicenter study to evaluate the best day for embryo transfer: does the outcome justify prolonged embryo culture?

PURPOSE: This study aimed to evaluate the best day for embryo transfer in a prospective unrestricted randomized multicenter trial. METHODS: Data were collected on a preformed Excel-sheet which contained random numbers from 1 to 5 for each subsequent patient as a preprogrammed day for embryo transfer. Information was requested on patient's age, indication for sterility treatment, stimulation protocol used, numbers of oocytes retrieved, fertilized oocytes, cryopreserved embryos, and cell stage of embryos transferred. RESULTS: A total of 329 embryo transfers were performed, resulting in 106 clinical pregnancies (32.2%). Pregnancy rates achieved were 20.0% on day 1, 30.4% on days 2 and 3, and 50.0% on days 4 and 5 (p = 0.03). CONCLUSIONS: Within the scope of the present randomized multicenter trial, embryo transfers performed on days 4 and 5 enhanced the pregnancy rate significantly, compared to those of days 1, 2, and 3.

Adult↗
PubMed1993

Effects of strain and embryo transfer model (embryos from one versus two donor does/recipient) on results of cryopreservation in rabbit.

Differential effects of 2 transfer models for normal thawed embryos of 1 donor doe were studied on the offspring rate and their embryo survival at birth from 3 selected rabbit strains (SY and SB: synthetic strains, NZ: New Zealand White). Morulae were obtained 64-66 h post-coitum from 93 adult does treated with 25 IU of hCG (SY:36, NZ:27, SB:30). Morphologically normal morulae were frozen in the presence of 1.5M DMSO and stored in liquid nitrogen. Normal thawed embryos were transferred into the oviducts of synchronized recipient does of the same strain 48 h after being injected with 25 IU of hCG (SY:28, NZ:21, SB:24). Each recipient received embryos from 1 (single transfer) or 2 different donor does (double transfer). Significant differences were observed in the post-thawing percentage of normal embryos between strains (SY:95 +/- 1% and SB:85 +/- 3%, P < 0.05; NZ: ,91 +/- 2%). After transfer, no significant differences were observed in pregnancy rate and offspring rate between the transfer models, whereas significant differences were only found in survival rate when all transfers were analyzed (double: 24 +/- 4% vs single: 14 +/- 3%, P < 0.05). An effect of strain was detected in the pregnancy rate (NZ: 33% vs SB: 71%, P < 0.05; SY: 61%) and in the survival rate per donor doe on pregnant recipient doe (SY: 42 +/- 5 vs SB: 19 +/- 5, P < 0.05; NZ: 34 +/- 7%). These results suggest a differential embryo sensitivity with respect to their genetic origin in both the freezing-thawing and transfer procedures.

Animals↗
PubMed2000

Embryo nutrition and energy metabolism and its relationship to embryo growth, differentiation, and viability.

Over the past decade there has been a resurgence of interest in the culture media used in clinical in vitro fertilization. Unfortunately, during this time more confusion than consensus appears to have developed regarding the composition of these media. In order to facilitate a clearer understanding of this field, it is important to understand the role of specific medium components and how their use is regulated by the embryo. The roles of the key nutrients glucose, pyruvate, lactate, and amino acids during the preimplantation period have therefore been presented. Analysis of how the embryo regulates the utilization of such nutrients has led to a clearer understanding of the embryo's requirements during the dynamic period of preimplantation development. From such information, sequential culture media have been developed along with novel noninvasive tests of embryonic viability. It is proposed that continued studies on the human embryo will lead to further improvements in embryo culture conditions and the optimization of viability assays, culminating in the ability to transfer single embryos for the majority of, if not all patients.

Amino Acids↗
PubMed1989

Addition of steroids to embryo-uterine monolayer co-culture enhances embryo survival and implantation in vitro.

Co-culture with a mixed cell monolayer established from trypsinized uterine tissue increased the numbers of embryos developing in a minimum essential medium beyond the hatching blastocyst stage in the 5-day period of culture to 56.0% (343/613) compared with 30.2% (93/308) for embryos cultured in medium alone. The inclusion of progesterone (3.2 x 10(-6), 3.2 x 10(-5), or 3.2 x 10(-4) M) or oestradiol (3.7 x 10(-5) M) to the co-cultures increased the mean percentage of embryos developing to the advanced stages to 72.7-78.4%. The addition of progesterone (3.2 x 10(-6) M) together with oestradiol (3.7 x 10(-5) M) resulted in additional improvement to a mean of 86.5% (787/910, P less than 0.001) but the combination was without significant effect on embryos cultured in media alone. Blastocyst viability was not impaired by co-culture as assessed in embryo survival following surgical transfer to pseudopregnant recipients. This study confirms the feasibility of establishing co-culture systems to facilitate investigation of pre-implantation events in vitro and highlights a role of steroid hormones in enhancing the capacity of uterine cells to support pre-implantation-stage embryos.

Animals↗
PubMed2001

Embryo donation: outcome and attitudes among embryo donors and recipients.

The outcome of an embryo donation programme was evaluated and attitudes among donors and recipients studied by means of a questionnaire survey. A total of 27 couples went through 54 treatment cycles with frozen-thawed embryos donated by other infertile couples. The indications for treatment were premature or incipient ovarian failure in combination with severe male factor infertility. The mean age of the recipient women was 36 years, and that of the recipient men was 35 years. The mean duration of infertility was 8 years (range 2-19 years). Forty-six couples donated 209 excess frozen embryos to the programme. The clinical pregnancy rate in the recipients was 27.8% (15/54) per embryo transfer. An average of 1.9 embryos were transferred on each occasion. The response rate to the questionnaire was high (80-91%). Significantly more recipients (69%) than donors (47%) considered that the child should be informed about the manner of conception (P < 0.05). Some 29% of recipients and 42% of donors thought that the child should receive identifying information concerning the donor couple. The interest of the offspring, not only as regards knowing his/her genetic origin but also knowing full-blood genetic siblings, should be kept in mind in embryo donation programmes.

Adult↗