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At least 199 records · Page 11Linked to original sources
PubMed1995

Cumulative number and morphological score of embryos resulting in success: realistic expectations from in vitro fertilization-embryo transfer.

OBJECTIVE: To define statistical thresholds for the number and morphological score of embryos transferred that would be predictive of reproductive success in an IVF program. DESIGN: A retrospective review of patient records. SETTING: The Mount Sinai Medical Center Assisted Reproductive Technologies Program. PARTICIPANTS: One hundred women who underwent IVF-ET for a diagnosis of tubal occlusion and later delivered viable infants. RESULTS: The mean number of embryos transferred before achieving live birth was 10.7 +/- 7.9 (mean +/- SD), with one half of patients achieving success within the first seven embryos transferred, and 95% achieving success within 25 embryos. For high quality embryos, the numbers were 7.5 +/- 6.3, 5, and 17, respectively, and, for the cumulative embryo score, a measure of both embryo morphology and metabolic activity, were 114.2 +/- 86.0, 83, and 280, respectively. Greater than 50% of live births occurred within the first two ET attempts. CONCLUSIONS: Although more than half of patients achieved reproductive success within the first two ETs and the first five high quality embryos transferred, after this threshold, fecundity declined rapidly. The calculation of cumulative embryo scores offered additional prognostic information. While all prior attempts to define IVF-ET failure have done so by including patients who did not become pregnant, we have found an analysis of our successes to be a useful adjunct in counseling patients.

Adult↗
PubMed1996

How many embryos should be transferred in in vitro fertilization and tubal embryo transfer?

In order to achieve higher pregnancy rates, more than one embryo is usually transferred in in vitro fertilization (IVF) programs. Tubal embryo transfer (TET) produces an even higher pregnancy rate. However, the number of embryos that should be transferred in TET programs remains to be clarified. We studied a series of 241 consecutive TET cycles and analyzed their clinical characteristics, embryo numbers, cumulative embryo score (CES), and pregnancy outcomes. The results demonstrated that 1) four embryos was an adequate number to obtain a satisfactory pregnancy rate and fewer multiple pregnancies, 2) older patients and cases with male factor had less chance of pregnancy and more than four embryos could be transferred, and 3) CES values > 40 were preferred, but for young patients with unusually high anxiety about multiple pregnancies, a CES of 21 to 40 was optimal. A policy of transfer that limits transfer to a maximum of two, three or four embryos is not suitable in all cases and other factors (eg, repeated IVF failure or older age) should be individually considered. Therefore, two equations utilizing CES, age and failure of previous TET as the factors were developed to help practitioners to evaluate how many embryos should be transferred on an individual basis.

Adult↗
PubMed1988

Ultrarapid freezing of early cleavage stage human embryos and eight-cell mouse embryos.

Early cleavage stage human embryos and 8-cell mouse embryos were snap-frozen after a brief exposure to high concentrations of dimethyl sulfoxide (DMSO; 2 or 3.5 M) and 0.25 M sucrose and thawed in a warm water bath. Eleven of 12 3- to 8-cell human embryos survived freezing and thawing with more than 50% of their original blastomeres intact. However, pregnancy was not initiated when the 11 embryos were transferred to six patients. It was shown that continuation of embryonic development in vitro and in vivo was significantly better when 8-cell mouse embryos were snap-frozen in 3.5 M DMSO than in 2 M DMSO. When frozen in 3.5 M DMSO, 78% of 8-cell embryos survived on thawing, 84% developed to blastocysts in vitro, 63% implanted, and 42% developed to fetuses. Ultrarapid freezing is a quick and inexpensive method for mouse embryo cryobanking, but further studies are required to confirm the viability of frozen human embryos.

Animals↗
PubMed2006

Comparative analysis of cell cycle events in zygotic and somatic embryos of Cyclamen persicum indicates strong resemblance of somatic embryos to recalcitrant seeds.

Embryo development and germination of Cyclamen persicum have been comparatively characterized for zygotic and somatic embryos with regard to mitotic activity and morphology in order to identify developmental abnormalities in somatic embryogenesis. Zygotic embryo development proved to be highly synchronous with distinct periods of cell division, cell elongation and embryo maturation within a total period of 17 weeks of seed development. Somatic embryo development was accomplished within only 3 weeks, resulting in a mixture of morphologically highly variable embryos. No distinct developmental periods could be identified and no reduction of the mitotic activity was discovered for non-desiccated somatic embryos. Controlled desiccation of somatic embryos severely reduced their germination rate, demonstrating resemblance of somatic embryos to recalcitrant seeds, whereas zygotic Cyclamen seeds could be characterized as typically orthodox.

Cell Cycle↗
PubMed1992

Development of reconstituted mouse embryos produced from bisected and electrofused pronuclear-stage embryos.

The present study was designed to investigate the in vitro and in vivo development potential of reconstituted mouse embryos produced by bisection and electrofusion of pronuclear stage embryos (PN-E). Pronuclear-stage ICR and F1 (C57BL x CBA) strain mouse embryos were bisected manually with a fine glass needle under the dissecting microscope to produce karyoplasts (KP) and cytoplasts (CP). The KP of ICR PN-E and CP of F1 PN-E (KP: ICR + CP:F1) or the KP of F1 PN-E and CP of F1 PN-E (KP:F1 + CP:ICR) were attached using phytohemagglutinin-P (PHA-P) and then electrofused. High fusion rates of the KP and CP of PN-E were obtained (93.5%). The fused embryos were encapsulated in alginate gel and cultured for 72 or 96 hours. The cleavage rates of reconstituted embryos were also high (98.8%). Developmental rates to the blastocyst stage in vitro for the 96-hour culture of reconstituted embryos were 68.9% (KP:ICR + CP:F1) and 78.4% (KP:F1 + CP:ICR). Furthermore, the developmental ability of reconstituted embryos in vivo was investigated, and some live young were obtained (KP:ICR + CP:F1, 7.5% and KP:F1 + CP:ICR, 10.8%). In this study, it was confirmed that reconstituted embryos produced by bisection and electrofusion of pronuclear stage embryos were able to develop into blastocysts in vitro and into live young in vivo.

Journal Article↗
PubMed1992

Effect of incubation volume and embryo density on the development and viability of mouse embryos in vitro.

The morphology, cleavage rate and viability of preimplantation embryos from random bred Swiss mice were assessed after culture in different incubation volumes and embryo densities. Decreasing the incubation volume, from 320 to 20 microliters, significantly increased blastocyst cell number (P less than 0.01) and embryo development after transfer (P less than 0.01). Increasing the number of embryos incubated per drop from 1 to 16 significantly increased the number of two-cell embryos reaching the blastocyst stage in 5 or 320 microliters. Culturing embryos in groups significantly increased blastocyst cell numbers in all volumes employed and elevated embryo viability. Such observations are consistent with the hypothesis that the preimplantation mammalian embryo produces a factor(s) which can stimulate its own development. The results of this study have implications for clinical in-vitro fertilization, where embryos are routinely cultured individually in relatively large volumes.

Analysis of Variance↗
PubMed1992

Can the mouse embryo provide a good model for the study of abnormal cellular development seen in human embryos?

Mouse 2-cell embryos arrested in development, either due to the effect of in vitro culture conditions ('2-cell block') or after exposure to the protein synthesis inhibitor anisomycin, were examined to determine the effect of the level of protein synthesis on development. The rate of protein synthesis was found directly to reflect the developmental potential of the embryos. Embryos cultured in the highest dose of the drug failed to divide and had the lowest rate of protein synthesis over the period of investigation, whereas untreated viable 2-cell embryos in the control group had the highest rate of protein synthesis and developed normally. Measurement of the nuclear DNA showed that both arrested and non-arrested embryonic cells completed DNA replication. Furthermore, drug-arrested embryos, like embryos which 'block' in culture, remained morphologically intact when left in culture. Disruption of the nuclear integrity and formation of micronuclei, as is frequently observed in arrested human embryos, was not seen in mouse embryos. These results indicate that developmentally arrested mouse embryos may not be a good model for studying cellular dysfunction in early human development. Experimentation using human material is required to address directly the problem of abnormal human development.

Animals↗
PubMed1983

Endogenous Gibberellin-Like Substances in Somatic Embryos of Grape (Vitis vinifera x Vitis rupestris) in Relation to Embryogenesis and the Chilling Requirement for Subsequent Development of Mature Embryos.

Endogenous gibberellin (GA)-like substances were examined in suspension cultures of somatic embryos of a hybrid grape (Vitis vinifera x Vitis rupestris) during embryogenesis, and in mature embryos chilled at 4 degrees C, and subsequently incubated at 26 degrees C with and without abscisic acid (ABA). The extract was separated into a nonpolar fraction (would contain GA-precursors); a fraction that would contain free GAs; and a highly H(2)O-soluble fraction (would contain GA glucosyl conjugates and very polar free GAs). Quantitation after SiO(2) partition chromatography was accomplished by microdrop and immersion dwarf rice bioassays. As embryogenesis developed, the free and highly H(2)O-soluble GA-like substances, expressed on a dry weight basis, decreased (however, they increased on a per embryo basis). Chilling at 4 degrees C for 1 week greatly increased activity of free GA-like substances (per g dry weight and per embryo), it then declined over the next three weeks of chilling. Activity (per g dry weight and per embryo) in the H(2)O-soluble fraction declined throughout chilling. Activity in the GA-precursor fraction, however, increased steadily with chilling (per g dry weight and per embryo). Incubation at 26 degrees C after chilling enhanced activity in the free GA and H(2)O-soluble fractions (per g dry weight and per embryo), but activity in the GA-precursor fraction dropped dramatically. Incubation at 26 degrees C with (+/-) ABA after chilling prevented germination and maintained high activity for GA precursors and less polar free GAs and low activity in the polar free GA and H(2)O-soluble fractions.Kaurene and kaurenoic acid were characterized in the GA-precursor fraction of chilled embryos by gas-liquid chromatography-mass spectrometry (GLC-MS). The existence of GA(4) and GA(9) in ABA-treated, chilled embryos was also confirmed by GLC-MS.

Journal Article↗
PubMedDate not supplied

Quick freezing of mouse embryos: freezing of inbred strains and 2- and 4-cell embryos by vitrification.

Murine embryos of mice of four different inbred strains and one hybrid strain were evaluated for their ability to survive quick freezing by post-thaw in vitro development. The embryos were transferred to an equilibration medium [10% 1,2-propanediol and 20% glycerol in modified PBS (mPBS)] for 10 minutes and frozen in a vitrification medium (25% glycerol and 25% 1,2-prapanediol in mPBS) by direct lowering into liquid nitrogen. Following thawing at 30 degrees C, dilution in 1 M sucrose in mPBS and washing in mPBS the embryos were cultured, and development was evaluated 24-28 hours later. The number of fertilized eggs obtained by superovulation differed among the strains. The survival rates evaluated by in vitro cultivation of the post-thawed inbred embryos varied from 50-85% depending on the genotype, whereas the normal live offspring from transfer of frozen-thawed embryos to recipient females confirms that the quick freezing method is an applicable method for storage of genetically defined mouse strains and stocks. The quick freezing technique was applied on 4- and 8-cell (day-3) mouse embryos of hybrids. The in vitro development of frozen thawed 4- and 8-cell embryos (23% and 21% respectively) was found to be significantly lower than that of frozen thawed morulae (89%). Permeation in glycerol-solutions before equilibration significantly increased survival of 4- and 8-cell embryos (66% and 77% respectively). By the use of dimethylsulfoxid (DMSO) in the permeation solutions an even higher survival rate was obtained in the cryopreservation of 8-cell mouse embryos (95%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Viability of nuclei of two-cell mouse embryos stored at 4 degrees C and fused with blastomeres of fresh two-cell embryos.

This study compares the resistance of the nuclei and the cytoplasm of two-cell mouse embryos to short-term storage at low temperature above 0 degrees C. Two-cell embryos were stored at 4 degrees C for 24-96 h in PB1 containing 0.25, 0.5, 0.75, and 1.0 M sucrose. The development to blastocysts in culture was highest in the presence of 0.5 M sucrose. However, only 3% of the embryos developed into blastocysts after 96 h of storage. On the other hand, the viability of the nuclei of two-cell embryos stored at 4 degrees C was significantly prolonged when they were transplanted into a blastomere of enucleated fresh F1 (C57BL/6JXCBA) two-cell embryos. The proportions of chimeric embryos that developed to blastocysts were 88, 67, 76, 71, 64, 45, 32, and 20% following storage for 0, 48, 72, 96, 120, 144, 168, and 192 h, respectively. In addition, there was no difference in the coat color of the young derived from nuclei stored at 4 degrees C or fresh nuclei, although the proportions of chimeric embryos that developed into live young after transfer tended to decrease with increased storage time. Moreover, the viability of nuclei stored at 4 degrees C for 192 h was confirmed in the germ cell population of chimeric mice mated with albino mice. These results demonstrated that the nuclei in the two-cell mouse embryos were more resistant to storage at low temperature than the cytoplasm.

Animals↗
PubMed2005

Ultrasound-guided miduterine cavity embryo transfer is associated with a decreased incidence of retained embryos in the transfer catheter.

After initiating a policy of ultrasound-guided miduterine cavity embryo transfer (ET) on August 1, 2001, the incidence of retained embryos in the transfer catheter declined significantly from 4.2% (46 of 1,101 ETs) during the time interval January 1, 2000 to July 31, 2001, to 0.7% (6 of 908 ETs) during the time interval August 1, 2001 to December 31, 2002. Blood on the transfer catheter (38% vs. 19%) occurred with significantly greater frequency at ET in which embryos were retained; ETs of > or =4 embryos were more likely to be associated with retained embryos than ETs of <4 embryos (3.7% vs. 2.2%), and both the clinical pregnancy rate (PR) and implantation rate (IR) were lower when embryo retention occurred at ET than they were when embryos were not retained (25% vs. 34% clinical PR; 12% vs. 19% IR).

Catheterization↗
PubMed2002

Pregnancy rates for grade 2 embryos following administration of synthetic GnRH at the time of transfer in embryo-recipient cattle.

To succeed with pregnancy a bovine embryo must overcome the luteolytic mechanism and achieve recognition of pregnancy. It is understood that well developed embryos are more successful in achieving recognition of pregnancy than poorly developed ones. Attempts have been made to assist this recognition of pregnancy by utilising a number of hormonal supplements with varying levels of success. A study was undertaken to test the hypothesis that supplementation with synthetic GnRH at the time of transfer of Grade 2 embryos will enhance pregnancy rates in recipients receiving this category of embryo. Pairs of fresh and frozen Grade 2 embryos (n = 38) from 34 donor animals were allocated to the trial. Thirty eight pairs of recipients were used and one of each pair was randomly assigned to receive treatment on the day of embryo transfer (Day 7) with 5 ml of gonadorelin, containing a synthetic gonadotrophin releasing hormone, 0.1 mg/ml. Pregnancy diagnosis was carried out from 42 days post-transfer by either palpation per rectum or ultrasound scanning. Treatment, embryo processing, side of transfer, parity of recipient, breed of recipient and breed of donor dam showed no statistically significant effect on pregnancy rate. The overall pregnancy rate in this study was within commercially accepted limits for Grade 2 embryos at 38.2%. The pregnancy rates were 34.2 and 42.1% for the GnRH-treated and control groups, respectively and were not significantly different at P < 0.05. The failure of this treatment to improve pregnancy rates could be due to its effect being transitory therefore allowing subsequent pregnancy loss. The timing of the treatment post-transfer, treatment dose and potency of the GnRH analogue may also play a role in this. Further study is required to determine the hormonal or follicular status of prospective candidates for treatment before applying this as a whole herd regime.

Animals↗
PubMed2004

Transfer of early-cleaved embryos increases implantation rate in patients undergoing ovarian stimulation and ICSI-embryo transfer.

The hypothesis that inspection for early cleavage improves pregnancy rate by aiding selection of the best embryos for transfer was tested in this study. Inspection for early cleavage was performed randomly in women undergoing intracytoplasmic sperm injection (ICSI) cycles. No differences were observed between early cleavage-inspected and uninspected embryos. When the hypothesis that transfer of early-cleaved (EC) embryos yields a higher pregnancy rate than transfer of late-cleaved (LC) embryos was tested using early cleavage-inspected cycles, it was found that transfer of EC embryos resulted in a higher implantation rate than transfer of LC embryos. In transfers for which all embryos were EC (100% EC), transfer of fewer embryos yielded a higher implantation rate compared with LC and uninspected cycles. These results indicate that, when inspected, early cleavage increases the implantation rate in ICSI patients.

Adult↗
PubMed2003

Embryo-maternal signalling: how the embryo starts talking to its mother to accomplish implantation.

The process of implantation and trophoblast invasion is currently considered as the most limiting factor for the establishment of pregnancy. Molecular interactions at the embryo-maternal interface during the time of adhesion and subsequent invasion are crucial to the process of embryonic implantation. Both partners, the mother as well as the embryo, play equal roles in the embryo-maternal dialogue, the embryonic part being the main topic in this study. Investigations of the proteins in the extra-embryonic matrices (i.e. zona pellucida) indicate that the embryo participates intensively in this early embryo-maternal signalling. One unique feature during implantation process of primate embryos is the release of chorionic gonadotrophin, which seems to influence endometrial activity by two different mechanisms: (i) luteotrophic activity with increasing progesterone release and (ii) a direct action on the endometrium. Furthermore, embryonic interleukin-1beta may be involved in embryo-maternal signalling. Other significant signals in this interaction are most likely leukaemia inhibitory factor (LIF) and colony-stimulating factor (CSF), which stimulate matrix metalloproteinase (MMP)/insulin-like growth factor binding protein-1 (IGFBP-1) activity and the insulin-like growth factor (IGF) system, which is modulated by embryonic IGFBP-3. Similar significances are discussed for uteroglobin and haptoglobin. Finally, the phenomenon of maternal immunological tolerance, triggered by the presence of the early embryo, is fundamental to the understanding of implantation and trophoblast invasion. A tightly regulated balance between activated and inactivated T cells at the implantation site may control the beginning of adequate trophoblast invasion and also limit this invasion to a tolerable extent for the maternal system, consequently ensuring a biologically healthy haemo-chorial placenta.

Animals↗
PubMedDate not supplied

The moral status of the embryo: the human embryo in the UK Human Fertilisation and Embryology (Research Purposes) Regulation 2001 debate.

The use of the embryo in research into birth defects, infertility and the possible therapeutic value of embryonic stem cells, has given rise to vigorous discussion of the ethical, moral and legal status of the embryo. This paper considers the parliamentary debate that surrounded the passing of legislation in the UK in 2000 governing the use of the embryo in research. Underlying disagreement by members of Parliament as to whether embryo research was permissible, were considerable differences regarding when life was thought to begin--whether at the moment of fertilization of the egg, or whether after 14 days, at the time of the beginnings of cell differentiation, and the point after which the embryo can no longer split to form twins. Those who favoured the latter view argued that, while the conceptus might possess a unique genetic formula, it had only the potential for life before 14 days, the development of human life being a gradual and continuous process. They considered it mistaken to accord the embryo full human rights. Those who adopted an opposed standpoint insisted that life was present and actual from the moment of conception and therefore sacrosanct and inviolable. The notion of the pre-embryo, they maintained, merely serves to disguise the embryo's humanity.

Bioethics↗
PubMedDate not supplied

Can embryo metabolism be used for selecting bovine embryos before transfer?

The quality of in vitro-produced bovine embryos remains variable. The selection of these embryos based only on their morphology does not allow for acceptable gestational rates to be obtained. The use of metabolic markers to select viable embryos before transfer would be of valuable help, both economically and as a research tool. The ideal marker should meet several conditions: it should be able to be evaluated 1) in a totally non-invasive manner, 2) on individual embryos (which necessitates very sensitive techniques), 3) very rapidly (so that it is compatible with the immediate transfer of fresh embryos), and 4) in order to allow viable embryos to be separated from those that are not viable, whatever the production system used. In practice, such a marker does not exist, but certain methods of metabolic evaluation resemble it. The development of a metabolic marker is confronted by the metabolic characteristics of the embryo, notably the evolution of the metabolism during the development of the embryo and its adaptation to the changes in the environment.

Adaptation, Physiological↗