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PubMed1989

Use of embryo transfer to induce twinning in beef cattle: embryo survival rate, gestation length, birth weight and weaning weight of calves.

Experiments were conducted in 1985 and 1986 at the Eastern Ohio Resource Development Center, Belle Valley, to examine the feasibility of using embryo transfer to induce twinning and to examine the influence of twinning on traits of the cow and calf. Embryos were collected from a total of 14 superovulated Angus donors on two dates each in 1985 and 1986 and were transferred to Angus recipients. A total of 124 embryos were transferred to 79 recipients, with 43 (34.7%) calves born alive. Seven of 45 (15.6%) recipients implanted with two embryos produced twins. In no case did both halves of the 15 embryos that were split to produce identical twins and implanted in the same recipient survive to birth. Proportion of calves born alive did not differ among transfer codes 3 (nonsplit embryos from two different donors implanted in separate uterine horns of the same recipient), 6 (nonsplit embryos from one embryo flush implanted in separate uterine horns of the same recipient) and 7 (nonsplit embryos from two different donors implanted in the same uterine horn of one recipient). Surgical transfers tended to result in a higher proportion of embryos surviving to birth (.43 vs .21; P = .16) and a higher twinning rate (.29 vs .04; P = .36) than did nonsurgical transfers. Age of recipient did not influence embryo survival (P = .98) or twinning rate (P = .99). Gestation length was 5 d shorter (P less than .01) for twin calves than for singles. Singles were 9 kg heavier (P less than .01) at birth and 32 kg heavier (P less than .01) at weaning than twins. However, cows raising twins produced 108 kg (51%) more total weaning weight than did cows raising singles.

Animals↗
PubMed1991

Cryopreservation of mouse zona-free embryos and embryos exposed to biopsy and reconstruction by vitrification in microdrops.

Zona-free zygotes, 2-cell, 4-cell, and 8-cell embryos, morulae, blastocysts and embryos exposed to biopsy and reconstruction were cryopreserved in microdrops of vitrification medium expelled directly into liquid nitrogen. While none of the zygotes and 2-cell embryos survived storage in liquid nitrogen, 54% 4-cell and 97% 8-cell embryos, 99% morulae, 88% blastocysts, 98% biopsied and 100% reconstructed embryos were intact one hour after thawing. Developmental potential of cryopreserved zona-free embryos evaluated after 30 h of in vitro culture was high. Of the frozen embryos, 49% 4-cell and 92% 8-cell embryos, 95% morulae, 79% blastocysts, 84% biopsied and 90% reconstructed embryos were capable of further cleavage. After the transfer of zona-free 8-cell embryos, morulae, blastocysts, biopsied and reconstructed embryos into day-1 recipients - 4 (16%), 14 (56%), 3 (12%), 0 and 8 (32%) live foetuses were recorded, respectively.

Animals↗
PubMed2000

Embryo implantation after biopsy of one or two cells from cleavage-stage embryos with a view to preimplantation genetic diagnosis.

Preimplantation genetic diagnosis (PGD) can be offered as an alternative to prenatal diagnosis (PND) to couples at risk of having a child with a genetic disease. The affected embryos are detected before implantation by fluorescent in situ hybridisation (FISH) for sexing (X-linked diseases) and chromosomal disorders (numerical and structural) or by polymerase chain reaction (PCR) for monogenic disorders (including some X-linked diseases). The accuracy and reliability of the diagnosis is increased by analysing two blastomeres of the embryo. However, the removal of two blastomeres might have an effect on the implantation capacity of the embryo. We have evaluated the implantation of embryos after the removal of one, two or three cells in 188 PGD cycles where a transfer was done. The patients were divided into five groups: a first group which received only embryos from which one cell had been removed, a second group which received only embryos from which two cells had been removed, a third group which received a mixture of embryos from which one and two cells had been taken, a fourth group where two and three cells had been removed, and a fifth group where three cells had been removed. The overall ongoing pregnancy rate per transfer was 26.1%, the overall implantation rate per transfer was 15.2% and the overall birth rate was 14.2%. Although pregnancy rates between the groups cannot be compared because the second group (two cells removed) contains more rapidly developing and therefore 'better quality' embryos, an ongoing pregnancy rate of 29.1% and an implantation rate of 18.6% per transferred embryo in this group is acceptable, and we therefore advise analysing two cells from a > or =7-cell stage embryo in order to render the diagnosis more accurate and reliable.

Biopsy↗
PubMed1999

Characterization of a top quality embryo, a step towards single-embryo transfer.

In most in-vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) programmes approximately one ongoing pregnancy in three is multiple. The need to characterize embryos with optimal implantation potential is obvious. We retrospectively examined all of 23 double transfers resulting in ongoing twins, occurring between January 1, 1996 and May 19, 1997. Characteristics of these top quality embryos were absence of multinucleated blastomeres, four or five blastomeres on day 2, seven or more cells on day 3, and </=20% anucleated fragments. In a subsequent series of 400 IVF/ICSI cycles (out of which 372 were selected for embryo transfer) from May 20, 1997 to July 31, 1998, only women <38 years of age had multiple pregnancies: after 221 transfers of two embryos, 45/116 (39%) were multiple, and after 77 transfers of >2 embryos, 11/31 (35%) were multiple. We applied our top quality criteria to the 221 double transfers: 106 transfers with two top embryos resulted in 65 (63%) ongoing pregnancies with 37 (57%) twins, 65 transfers with one top embryo in 38 (58%) ongoing pregnancies with eight (21%) twins. In the group without top embryos, 12/52 (23%) ongoing singletons occurred, with no twins. The corresponding ongoing implantation rates were 49, 35 and 12%. This analysis suggests that single embryo transfer with an acceptable pregnancy rate might be considered if a top quality embryo is available.

Blastomeres↗
PubMed2006

Metabolism of human embryos following cryopreservation: implications for the safety and selection of embryos for transfer in clinical IVF.

BACKGROUND: Cryopreservation of supernumerary embryos is routinely performed in human-assisted reproduction, providing a source of embryos which can be thawed for use in subsequent treatment cycles. However, the viability of cryopreserved embryos has traditionally relied on morphological assessment, which is a poor predictor of embryo health since freezing leads to a significant overall reduction in implantation potential, and its long-term efficacy is unknown. This study describes how the post-thaw metabolism of human embryos can be used to predict future development to the blastocyst stage. METHODS: HPLC was used to analyse the post-thaw amino acid metabolism of human embryos from day 2 to day 3 of development. RESULTS: It was possible to predict with 87% accuracy which frozen-thawed embryo would develop to the blastocyst stage. Developmentally competent embryos were more metabolically quiescent than their arresting counterparts. Amino acid turnover was also capable of distinguishing between the developmental potential of the best, Grade I embryos P < 0.05. CONCLUSIONS: The data suggests that cryopreservation in IVF is a safe procedure and that amino acid turnover can be used to select which cryopreserved embryo will develop to the blastocyst stage, irrespective of their post-thaw grade.

Amino Acids↗
PubMed1992

Use of ethylene glycol as a cryoprotectant for bovine embryos allowing direct transfer of frozen-thawed embryos to recipient females.

Four experiments were conducted to define a system for the direct transfer of frozen-thawed bovine embryos to recipient females. In Experiment I, nonsurgically recovered embryos were frozen in 1.5 M ethylene glycol (EG), 1.5 M propylene glycol (PG), 1.5 M DMSO or 1.4 M glycerol (GLY), and then thawed and placed directly into holding medium. Viability at 72 hours of post-thaw culture was 70, 11, 25 and 30% for the four groups, respectively. In Experiments II and III, 1.0, 1.5 and 2.0 M concentrations of EG were compared; a concentration of 1.5 M appeared to provide optimal cryopreservation and survival after direct rehydration. In Experiment IV, embryos were packaged in straws containing only 1.5 M EG, in straws containing a column of 1.5 M EG and the embryo and two columns of PB1 in a 1:3 ratio of volumes (EG PB1 ), or were frozen in 1.4 M glycerol. After thawing, embryos in EG and EG PB1 treatments were transferred directly to recipient females, while embryos frozen in GLY were rehydrated using a three-step procedure. In the first trial, pregnancy rates at approximately 60 days of gestation for embryos frozen in EG and GLY groups were 39 and 62%, respectively (P<0.10). In the second trial, the pregnancy rate for embryos frozen in EG PB1 was equal to that of embryos frozen in GLY (50% in both groups). These experiments demonstrate the potential for using ethylene glycol as a cryoprotectant for bovine embryos, thus permitting direct transfer of frozen-thawed embryos to recipient females.

Journal Article↗
PubMed2004

Elevated incidence of chromosomally chaotic embryos among frozen-thawed preimplantation embryos.

OBJECTIVE: The aim of the study was to evaluate the effect of cryopreservation on the formation of chromosomal abnormalities in human preimplantation embryos. STUDY DESIGN: The chromosomal constitutions of cleavage stage embryos (n = 61) were assessed using fluorescent in situ hybridisation (FISH) technique, applying probes for chromosomes 13, 16, 18, 21, X and Y. Study group embryos frozen at zygote or two-cell stage (n = 29) were cultured in vitro post-thawing until they reached four- to six-cell stage, after which their chromosomal constitutions were assessed. Control group embryos frozen at four- to six-cell stage (n = 32) were analysed immediately after thawing in order to exclude any post-thaw effect. The proportions of genetically normal and abnormal embryos were compared between study and control group. RESULTS: The proportions of normal, aneuploid and mosaic embryos were similar in both groups. However, significantly (P < 0.05) higher proportion of chaotic embryos in study (24.1%) compared to control group (6.3%) was observed. CONCLUSION: The elevated level of chromosomally chaotic embryos among embryos that had undergone cellular division after thawing as compared to embryos analysed immediately after thawing indicates a potential negative impact of cryopreservation on the formation of chromosomal abnormalities in preimplantation embryos.

Adult↗
PubMed1997

Effects of co-culture and embryo number on the in vitro development of bovine embryos.

It is generally accepted that culturing embryos in groups or with somatic cells improves both the yield and quality of the blastocysts obtained. The aims of this study were 1) to compare the yield and quality of the embryos obtained after culture in several number conditions and in several culture systems and 2) to assess the effect of co-culture started at various stages of embryo development. Under cell-free culture conditions (modified synthetic oviduct fluid [mSOF] supplemented with 10% fetal calf serum [FCS] 48 h post insemination, the rate of Day 10 blastocysts was lower when embryos were cultured in small groups (1 to 6 per drop) than in large groups (4 versus 23% ; P < 0.01). There was no group effect when embryos were co-cultured either with Buffalo rat liver (BRL) cells in TCM 199, or in a culture system allowing the progressive development of cumulus cells in mSOF, even if co-culture started at 66 or 114 h post insemination. However, embryos cultured singly had lower cell numbers than embryos cultured in large groups when co-culture started at 114 h post insemination. This suggests that 1) somatic cells improve the development of singly cultured bovine embryos up to the blastocyst stage after the 9-16 cell stage; 2) co-culture affects blastocyst cell number of singly cultured embryos by acting roughly between the 5-8 and the 9-16 cell stage; and 3) cooperation between embryos could replace the effect of co-culture either on the yield of blastocysts or on blastocyst cell number. Blastocysts appeared significantly earlier in co-culture with cumulus cells in mSOF than in co-culture with BRL cells in TCM 199 (detection of the blastocysts: 7.3 +/- 0.1 d post insemination with cumulus cells versus 8.1 +/- 0.1 d with BRL cells; P < 0.001) and had a significant higher number of cells (143 +/- 9 versus 85 +/- 11; P < 0.001). This system thus seems suitable for the culture of small numbers of embryos resulting from in vitro maturation and fertilization of oocytes from individual donor cows.

Journal Article↗
PubMed2003

Microspore-derived embryos from Quercus suber anthers mimic zygotic embryos and maintain haploidy in long-term anther culture.

Microspore-derived embryos produced from cork oak anther cultures after long-term incubations (up to 10-12 months) were analysed in order to determine the genetic variability and ploidy level stability, as well as morphology, developmental pattern and cellular organisation. Most of the embryos from long-term anther cultures were haploid (90.7%), corresponding to their microspore origin. The presence of a low percentage of diploid embryos (7.4%) was observed. Microsatellite analysis of haploid embryos, indicated different microspores origins of the same anther. In the diploid embryos, homozygosity for different alleles was detected from anther wall tissues, excluding the possibility of clonal origin. The maintenance of a high proportion of haploid embryos, in long-term anther cultures, is similar in percentage to that reported in embryos originating after 20 days of plating (Bueno et al. 1997). This suggests that no significant alterations in the ploidy level occurred during long incubations (up to 12 months). These results suggest that ploidy changes are rare in this in vitro system, and do not significantly increase during long-term cultures. Microscopical studies of the microspore embryos in various stages revealed a healthy and well developed anatomy with no aberrant or chimeric structures. The general morphology of embryos appearing at different times after plating, looked similar to that of earlier embryos, as well as the zygotic embryos, indicating that they represent high quality material for cork oak breeding.

Cell Culture Techniques↗
PubMed1997

Effect of embryo density and growth factors on in vitro preimplantation development of mouse embryos.

Embryo development depends on maternal and embryonic factors that may regulate genetic programs in early development. Effects of growth factors on proliferation, differentiation and morphogenesis along embryogenesis have been documented. However, studies have not established the role of growth factors in the preimplantational period. The purpose of this study was to investigate the possible effects of growth factors and embryo density on mouse preimplantation development in vitro. Two- and eight-cell CF-1 embryos were cultured individually or in groups of ten in HTF medium, alone or with EGF, TGF-beta 1 and IGF-I. Cleavage rate varied greatly with growth factors and increased significantly when eight-cell embryos were cultured in groups. On the other hand, when two-cell embryos were cultured in groups, the cleavage rate was slower than that obtained when embryos were individually cultured. The differentiation rate increased significantly in two-cell embryos cultured in groups (p < 0.05). EGF, TGF-beta 1 and IGF-I increased differentiation rates significantly in two-cell embryos individually cultured for 68 hours. The combination of EGF and TGF-beta 1 increased the differentiation rates significantly. The other combinations were not effective in modifying this parameter. Hatching rates increased in embryos cultured in groups (p < 0.05). TGF-beta 1 decreased this parameter significantly in two- or eight-cell embryos cultured in groups (p < 0.05). The data described in this report suggest that preimplantational mouse embryos produce some factor or factors that enhance its development, specially the differentiation and hatching rates. However, a functional role for polypeptide growth factors during preimplantational development has to be determined.

Animals↗
PubMed2007

Graduated Embryo Score and soluble human leukocyte antigen-G expression improve assisted reproductive technology outcomes and suggest a basis for elective single-embryo transfer.

OBJECTIVE: To evaluate assisted reproductive technology (ART) outcomes by using Graduated Embryo Score (GES) and soluble human leukocyte antigen-G (sHLA-G) expression to select embryos for transfer on day 3. DESIGN: Prospective cohort. SETTING: Private practice. PATIENT(S): Women undergoing fresh ART cycles (n = 209). INTERVENTION(S): In vitro fertilization using standard protocols. Embryos scoring GES of > or =70 using were selected for transfer on the basis of sHLA-G expression in the culture media on day 2. MAIN OUTCOME MEASURE(S): Pregnancy, implantation, and multiple-gestation rates. RESULT(S): Ongoing gestations increased with the number of embryos expressing sHLA-G (37%, 42%, 58%, and 56% with 0, 1, 2, or 3 sHLA-G(+), respectively). With at least two sHLA-G(+) embryos, ongoing gestation and implantation rates were higher than those with fewer than two sHLA-G(+). Differences were even higher for women aged < or =37 years. With at least two sHLA-G(+) embryos, the odds ratio (95% confidence interval) was 1.59 (1.51-1.68) for ongoing gestation compared with the case of fewer than two sHLA-G(+). Age was the most important predictor of outcome; the odds ratio (95% confidence interval) was 2.07 (1.98-2.16) for ongoing gestation in women aged < or =37 years with at least two sHLA-G(+) embryos, compared with the case of women aged 38-40 years. CONCLUSION(S): Day 3 embryo transfer using GES and sHLA-G improves ART outcomes by increasing predictive accuracy. High twin rates suggest that couples with at least two sHLA-G(+) embryos consider elective single-embryo transfer.

Adult↗
PubMed1996

A prospective, randomized study of embryo transfer results after 3 or 5 days of embryo culture in in vitro fertilization.

OBJECTIVES: To compare the implantation rate of embryos after 3 and 5 days of IVF culture. DESIGN: Prospective randomization of ET depending on the weekday of ovum pick-up (OPU). SETTING: University Department of Endocrinology and Reproduction. PATIENTS: All women entering an outclinic IVF program. INTERVENTIONS: Two hundred thirty-three ETs performed on day 3 after OPU and 410 performed on day 5 were analyzed. When blastocysts with a clear inner cell mass were available, a maximum of two were replaced. RESULTS: On day 3 after OPU, 60 pregnancies per 233 ET (26%) and on day 5, 102 pregnancies per 410 ET (25%) were induced. The average implantation rate per embryo was 13% and 12%, respectively. After subdivision according to embryo morphology, pregnancy rate per ET (n = 59) and implantation rate per embryo on day 3 with exclusively unfragmented embryos were 32% and 18%, respectively, not significantly different from ET (n = 73) exclusively with embryos containing > 0% and < 20% fragments: 27% and 12%. After transfer on day 5, when one or more cavitating embryos were available (n = 227), pregnancy and implantation rates were 40% and 23%, statistically different from ET on day 3. On day 5, ET exclusively with morula stages showing signs of starting blastulation (n = 26), pregnancy rate and implantation rate were 12% and 11%, respectively, from ET (n = 157) with embryos not reaching the latter stage: 6% and 3%. CONCLUSIONS: Overall ET results after 3 and 5 days are comparable. After 5 days of culture, one to two embryos can be replaced with an average implantation rate of > 23% per embryo, minimizing the incidence of triplets.

Blastocyst↗
PubMed2006

Metabolic regulation of in-vitro-produced bovine embryos. I. Effects of metabolic regulators at different glucose concentrations with embryos produced by semen from different bulls.

The toxic and/or beneficial effects of four metabolic regulators on embryo development were evaluated. In-vitro-produced compact morulae were cultured for 3 days in a chemically defined medium + bovine serum albumin (BSA; CDM-2) plus regulators (4991 total embryos). Phenazine ethosulfate (PES), phloretin (PL), pyrroline-5-carboxylate (P5C), and sodium azide (NaN3) were evaluated at four doses each in factorial combinations with four concentrations of glucose: 0, 0.5, 2, and 8 mm. Phenazine ethosulfate at 0.9 microm resulted in poorer development than lower or no PES. Phloretin was, in general, detrimental for embryo development, but most markedly at the highest dose (270 microm). Pyrroline-5-carboxylate had little effect on post-compaction embryos at the doses studied, 9 to 81 microm. Sodium azide at the concentrations used (3, 9, and 27 microm) had little effect on embryo development compared with controls. Concentrations of glucose had little effect on development of embryos. A fifth metabolic regulator, 2,4-dinitrophenol (DNP), was studied at various doses at pre-morula or morula-blastocyst stages cultured in 2 mm glucose. Embryos (2189 total) cultured in 90 microm DNP developed more slowly and were darker than embryos cultured at lower doses. Embryos cultured in 30 microm DNP had a higher blastocyst rate (48.3%) than controls (34.9%). In the last experiment using G1.2/G2.2 media, DNP (30 microm) resulted in a marked decrease in embryonic development when embryos were exposed at the zygote to 8- to 16-cell stages but had little effect when morulae were exposed for 2 days. The dose-response information for these metabolic regulators is crucial for designing future experiments.

2,4-Dinitrophenol↗
PubMed1998

Vitrification of human embryos based on the assessment of suitable conditions for 8-cell mouse embryos.

Experiments were conducted to find a suitable cryoprotectant and suitable procedure for vitrification of 8-cell mouse embryos. The method was then applied clinically to the cryopreservation of human embryos in our assisted reproduction programme. Mouse embryos were vitrified with 30 or 40% 1,2-propanediol (PROH), dimethylsulphoxide (DMSO), ethylene glycol, glycerol, or acetamide, each diluted with a solution containing 30% Ficoll plus 0.5 M sucrose. Embryos were exposed to the solutions for 0.5 or 2 min at 20 or 25 degrees C, cooled in liquid nitrogen and warmed rapidly. Embryo survival was assessed by in-vitro development. In PROH-, DMSO- and acetamide-based solutions, higher survival rates (29-82%) were obtained with less permeating conditions, suggesting that these cryoprotectants are considerably toxic. In glycerol- and ethylene glycol-based solutions, however, higher survival rates (74 and 92% respectively) were obtained with more permeating conditions, suggesting that these cryoprotectants are less toxic. Human embryos on days 2-3 were vitrified in an ethylene glycol-based solution (EFS40). Survival, assessed by the morphology, was higher in 4-cell embryos on day 2 and 8-cell embryos on day 3 than in 2-3-cell embryos on day 2 or 2-7-cell embryos on day 3. From 18 transfers, one ended with the delivery of healthy twin babies.

Animals↗
PubMed2004

Comparative analysis of pregnancy rates after the transfer of early dividing embryos versus slower dividing embryos.

BACKGROUND: We compared retrospectively the pregnancy outcome in two subgroups of ICSI patients, using early division (26 h post injection) to the 2-cell stage as a criterion for embryo quality and viability (ability to produce a pregnancy). METHODS AND RESULTS: In the early dividing embryo (EDE) group, at least one of the transferred embryos was early dividing. In the late dividing embryo (LDE) group, no early dividing embryo was transferred. Additionally, tubal and uterine transfer in the two groups was also evaluated. Clinical pregnancy rates in the EDE group were significantly increased when compared with that in the LDE group (41.3 versus 20.0%). This was also true for ongoing pregnancy rates (33.3 versus 16.3%). The tubal transfer route showed increased (but not significant) ongoing pregnancy rates when compared with uterine transfer in both EDE (38.5 versus 25.0%) and LDE (22.7 versus 8.3%) groups respectively. In uterine transfer cycles, however, clinical pregnancy rates for EDE were significantly increased compared to LDE (37.5 and 11.1% respectively). The baby rate (number of live babies/embryos transferred) was also significantly increased in the EDE group and the tubal transfer group. Statistical analysis of pregnancy outcome, adjusted for the total number of embryos transferred (expressed as percentage risk difference - %RD), resulted significantly in favour of EDE compared to LDE (RD = 18%, P = 0.02). When adjusted for the combined factors: total number of embryos transferred, EDE and LDE, the pregnancy outcome result was significantly in favour of tubal transfer compared to uterine transfer (RD = 15%, P = 0.05). Pregnancy results of the LDE group only were significantly better in the tube compared to the uterus (RD = 19%, P = 0.04) but not significantly so for the EDE group (RD = 10%, P = 0.4). CONCLUSION: Early division is associated with embryo quality and a very easy and successful embryo transfer selection method. Our results also suggest that when EDE are available, both tubal and uterine embryo transfer can be considered. When only LDE are available, however, tubal transfer should be the preferred transfer route.

Adult↗
PubMed2005

The implantation of every embryo facilitates the chances of the remaining embryos to implant in an IVF programme: a mathematical model to predict pregnancy and multiple pregnancy rates.

BACKGROUND: We aimed to assess the validity of a theoretical mathematical model to predict the pregnancy rate and the multiple pregnancy rate in IVF/oocyte donation programmes on the basis of the implantation rate and the number of transferred embryos. METHODS: A total of 1835 embryo transfers corresponding to three different programmes in two centres with different implantation rates were analysed. Pregnancy and multiple pregnancy rates observed in the aforementioned programmes were compared with those obtained following different mathematical models. Four models were tested: binomial model, ground model, maternal variability model and collaborative model. The goodness of fit was performed by means of the maximum likelihood fit method. RESULTS: The binomial model could not predict the pregnancy rate, and especially the multiple pregnancy rate. The multiple pregnancy rate predicted following the binomial model was much lower than observed, up to 40-fold reduced. Ground model and maternal variability model adjusted to the data with more precision, but were still not accurate. Finally, the collaborative model reproduced with very great accuracy both pregnancy rate and the multiple pregnancy rate. A collaborative parameter of 22% was found, implying that the implantation probability of each embryo is increased by 22% for every embryo previously implanted. CONCLUSIONS: Embryonic implantation does not follow a binomial law, showing that the implantation is not independent from the number of embryos implanted. The best fit to the data is obtained following a collaborative model by which the implantation of one embryo is facilitated by the implantation of other embryo(s). The mathematical formula of the collaborative model predicts very accurately the pregnancy rate and the multiple pregnancy rate in IVF/oocyte donation programmes, based on the implantation rate of this specific programme and the number of embryos transferred up to five embryos. We recommend using the aforementioned formula to quantify the pregnancy rate and the risk of multiple pregnancy in the counselling of the infertile couple at embryo transfer. Such a formula is freely available at www.ifca.unican.es/matorras/mathpreg/.

Embryo Implantation↗
PubMed1996

Regulation of urokinase plasminogen activator production in implanting mouse embryo: effect of embryo interaction with extracellular matrix.

Embryo implantation in the mouse is an invasive process and requires the action of proteinases, including plasminogen activator (PA) and metalloproteinases. After the implanting embryo establishes close contact with the endometrium, the invasion process begins, at least in part, through interactions of the embryo with the extracellular matrix in the endometrium. This study determined whether embryo interaction with extracellular matrix components would affect the secretion of PA in vitro. PA in vitro. Mouse embryos were collected from the uterus on Day 3.5 of development, just before implantation, and were cultured dishes precoated with bovine serum, plasma fibronectin, or BSA (control). Embryos cultured on serum- or fibronectin-coated dishes secretes significantly more PA than those cultured on BSA. The effect of fibronectin was inhibited by hexapeptides that contained the integrin-recognizing Arg-Gly-Asp sequence. This indicates that the action of fibronectin in enhancing PA secretion is mediated through its receptor (integrins) in the embryo. Fibronectin fragments reproduced the effect of the whole fibronectin molecule, suggesting that the clustering of integrins by specific ligands is responsible, at least in part, for the increase PA secretion. The increase in PA secretion was a specific response to fibronectin rather than a reflection of increased total protein secretion, and was at least partially a result of the increased steady-state level of PA mRNA in the cultured embryos. Laminin was as effective as fibronectin in promoting PA secretion. Epidermal growth factor increased PA secretion, probably by promoting the interaction of the embryos with the extracellular matrix. In summary, our findings indicate that the interactions of the implanting embryos with their extracellular matrix may regulate trophoblast invasion by controlling PA secretion.

Amino Acid Sequence↗
PubMed2005

Comparison of two sequential media for culturing cleavage-stage embryos and blastocysts: embryo characteristics and clinical outcome.

This study was undertaken to compare the outcome of day 3, day 5, and frozen-thawed embryo transfer cycles where embryo culture was undertaken using the G1.2-G2.2 versus GIII series sequential media. A total of 400 day 3, 73 day 5 and 126 frozen-thawed embryo transfer cycles were analysed. Treatment cycles were quasi-randomized on the day of oocyte retrieval to embryo culture in G1.2-G2.2 versus GIII series sequential media. Randomization was undertaken according to alternating weekdays. Significantly more embryos were of grade 1 or 2 quality on day 3 in the GIII group (P < 0.05). Likewise, more embryos in the GIII group had eight blastomeres on day 3 (P < 0.05) and were able to hatch spontaneously (P < 0.05). For day 3 embryo transfer cycles, implantation and clinical pregnancy rates were 14.4 and 25.7% versus 37.8 and 50.3% in G1.2-G2.2 and GIII groups respectively (P < 0.05). For day 5 embryo transfer cycles, implantation rates were significantly higher (29 versus 45%; P < 0.05) in the GIII group. There was a trend towards higher pregnancy rates; however, this did not reach statistical significance due to fewer cycles analysed in this group. In-vitro culture in GIII series sequential media yields better quality embryos that implant more efficiently, compared with culture in G1.2-G2.2 media.

Blastocyst↗