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[Overcoming the "2-cell block" in mouse embryos in aggregation chimeras].

The embryos of the inbred mouse strain BALB/c are predisposed to so-called "two-cell block" after explantation from the maternal organism before the late two-cell stage and cultivation in a standard synthetic medium. Hybrid embryos (CBA x C57B1) F2 are competent to complete preimplantation development in vitro. The BALB/c embryo predisposed to block ("blocking") at the early two-cell stage was aggregated using phytohemagglutinin with four to five two- and eight-cell BALB/c embryos capable of reaching the blastocyst stage in vitro ("non-blocking"). This aggregate successfully developed until the blastocyst stage for 72 h. The aggregation of the early two-cell BALB/c embryos with each other did not prevent the block. After the aggregation of the blocking and non-blocking embryos at the two-cell stage, a common integrated blastocyst developed. In aggregates with eight-cell embryos, the blocking embryo formed a separate blastocyst, although it preserved contacts with non-blocking embryos during the entire period of cultivation. Ultrastructural analysis has shown that two-cell embryos aggregated using phytohemagglutinin form adhesive contacts up to several microns long. Possible mechanisms of cooperation between the competent and deficient partners in aggregates with two-cell embryos are discussed.

Animals↗

PubMed1997

Decreased catalase activity in malformation-prone embryos of diabetic rats.

The risk for congenital malformation is increased in diabetic pregnancy. An excess of radical oxygen species (ROS) in the embryo has been suggested as a major teratogenic mechanism. We have used 2 rat strains, denoted H and U, with different catalase isoenzymes to study if the type of ROS scavenging enzyme may be of importance for the embryonic dysmorphogenesis in diabetic pregnancy. Rats were mated H x H and U x U, and about half of the females had streptozotocin-induced diabetes. Embryos were harvested from female rats on day 11 and day 20 of pregnancy. On day 11, the H embryos showed larger crown-rump length (3.9 mm) than the U embryos (2.9 mm), a difference that remained in the embryos of diabetic rats (3.1 mm and 2.5 mm in the H and U strains, respectively). H embryos displayed higher activity of catalase (1.8 +/- 0.1 U/micrograms DNA) than U embryos (1.1 +/- 0.1 U/micrograms DNA), and the difference increased further when the H and U mothers were diabetic (H: 2.1 +/- 0.2 U/micrograms DNA, U: 0.6 +/- 0.1 U/micrograms DNA). In the day-20 fetuses, diabetes in the mother caused increased resorption rate in both strains (from 3.2% to 10.6% in H rats, from 6.8% to 39.5% in U rats), and high rate of congenital malformations in the U strain (H: 0% malformations, U: 20% malformations). We found a strain-related difference in embryo catalase activity with higher activity in the teratogenically resistant H embryos compared to the malformation-prone U embryos. Provided that this difference between the strains signifies a genetic difference of functional antioxidative importance, the results may suggest that catalase enzyme activity has a protective role in opposing embryonic dysmorphogenesis in diabetic rat pregnancy.

Abnormalities, Drug-Induced↗

PubMed1992

Effects of oxygen toxicity on early development of mouse embryos.

To examine the effects of oxygen toxicity on embryonic development, mouse pronuclear embryos were cultured under low oxygen conditions with or without superoxide dismutase (SOD), and the blastulation rate was compared with that of embryos cultured under standard conditions. The blastulation rate of mouse pronuclear embryos cultured under standard conditions was only 1.5% (2/131). This rate was increased significantly, to 28.5% (43/151), when the embryos were cultured under low oxygen conditions; and to 31.0% (35/113) when SOD (500 micrograms/ml) was added to the medium under standard conditions; the rate was increased to 75.2% (115/153) when the embryos were cultured under low oxygen conditions in the presence of SOD. The minimum effective concentration of SOD in the culture medium was 50 micrograms/ml under conditions of 5% O2. The blastulation rate was significantly decreased after 1-hr exposure of pronuclear embryos to room atmospheric oxygen concentration (20% O2), and subsequent culture under 5% O2 with SOD did not result in an improved blastulation rate. Culture with SOD under 5% O2 promoted the development of two-cell stage embryos to the blastocyst stage. When two-cell stage embryos were collected 48 hr after hCG and cultured for 66 hr, their blastulation rate was similar to that of embryos collected from mice 114 hr after hCG. These results suggested that embryonic development in vitro is greatly affected by atmospheric oxygen throughout the early embryonic stages and that this harmful effect can be prevented by culturing embryos under low oxygen conditions and in the presence of SOD.

Animals↗

PubMed2006

Nucleoplasmin facilitates reprogramming and in vivo development of bovine nuclear transfer embryos.

Successful cloning by somatic cell nuclear transfer (NT) involves an oocyte-driven transition in gene expression from an inherited somatic pattern, to an embryonic form, during early development. This reprogramming of gene expression is thought to require the remodeling of somatic chromatin and as such, faulty and/or incomplete chromatin remodeling may contribute to the aberrant gene expression and abnormal development observed in NT embryos. We used a novel approach to supplement the oocyte with chromatin remodeling factors and determined the impact of these molecules on gene expression and development of bovine NT embryos. Nucleoplasmin (NPL) or polyglutamic acid (PGA) was injected into bovine oocytes at different concentrations, either before (pre-NT) or after (post-NT) NT. Pre-implantation embryos were then transferred to bovine recipients to assess in vivo development. Microinjection of remodeling factors resulted in apparent differences in the rate of blastocyst development and in pregnancy initiation rates in both NPL- and PGA-injected embryos, and these differences were dependent on factor concentration and/or the time of injection. Post-NT NPL-injected embryos that produced the highest rate of pregnancy also demonstrated differentially expressed genes relative to pre-NT NPL embryos and control NT embryos, both of which had lower pregnancy rates. Over 200 genes were upregulated following post-NT NPL injection. Several of these genes were previously shown to be downregulated in NT embryos when compared to bovine IVF embryos. These data suggest that addition of chromatin remodeling factors to the oocyte may improve development of NT embryos by facilitating reprogramming of the somatic nucleus.

Animals↗

PubMed2002

Early developing embryos affect the gene expression patterns in the mouse oviduct.

Fertilization and development of mouse embryos occur in the ampullae of oviduct. We hypothesize that fetal-maternal communication exists in the preimplantation period, allowing optimal development of embryos. It is known that embryotrophic factors from oviduct affect the development of embryos. Although embryos affect their own transport in the oviduct, the mechanism of action is unknown. As a step toward understanding the action of embryos on oviductal physiology, we adopted suppression subtractive hybridization (SSH) to compare the gene expression in the mouse oviduct containing early embryos with that of oviduct containing oocytes. Ten to twelve 1-cell mouse embryos were transferred to one oviduct of a foster mother and similar number of oocytes were transferred to the contralateral oviduct. The animals were sacrificed after 48 h and their oviducts were excised for mRNA study. Using SSH, we screened out 250 putative positive clones from the subtracted embryo-containing oviduct library and 97 of them were screened positive by reverse dot-blot analysis. DNA sequence analysis identified genes that shared high homology with sequences in GenBank/EMBL database with unknown functions. Overall, 13 of the 90 high-quality sequences (14%) were homologous to 6 different genes previously described. Reverse Northern analysis confirmed that the expression of these genes were higher in the embryo-containing oviduct than in the oocyte-containing oviduct. About 12% of these clones (11/90) were novel. This article is the first to report identification of genes in the oviduct that are upregulated in the presence of embryos during the preimplantation period.

Animals↗

PubMed1993

Cryopreserved mouse embryos can successfully survive biopsy and refreezing.

OBJECTIVE: We examined whether cryopreserved mouse eight-cell embryos could be thawed, biopsied, refrozen, thawed, and grown in vitro and in vivo in two sets of experiments. METHOD: In the in vitro studies, the blastulation rate of cryopreserved embryos which had been thawed-->biopsied-->refrozen-->thawed-->grown 48 hr in vitro were compared with that of sham-operated (zona dissected) and untreated control embryos (twice frozen only). For the in vivo studies, five control embryos were transferred to one horn and five experimental embryos were transferred to the contralateral horn of day 3 pseudopregnant recipient female mice. Recipient mice were sacrificed on day 18. RESULTS: The day 2 blastulation rate was the same for the control, sham-operated, and biopsied embryos when examined in vitro. In the first set of in vivo studies, 42.7% of control and 39.7% of sham-operated embryos that had been transferred implanted, and most embryos progressed to day 18. In the second set, 45.6% (57/125) and 39.7% (49/125), respectively, of the transferred embryos progressed to day 18 fetuses. There were no significant differences in the rate of fetal development in the different groups. CONCLUSIONS: These studies demonstrate that cryopreserved mouse eight-cell embryos can successfully undergo thawing, biopsy, and refreezing. The results suggest that under certain conditions, it may be possible to utilize cryopreservation in strategies involving human genetic diagnosis in the preimplantation period.

Animals↗

PubMed1996

Pregnancies after transfer of ultrarapidly frozen human embryos.

PURPOSE: We report our experience of freezing human embryos using an ultrarapid freezing method. METHODS: The patients were superovulated. Oocytes were inseminated and cultured in HTF + 10% serum. A maximum of three embryos was transferred and the rest of the embryos were frozen ultrarapidly after a 3-min equilibration period in PB1 + 3.5 M DMSO + 0.25 M sucrose. Embryos were thawed in a 37 degrees C water bath for 6 sec, then cultured in PB1 + 20% serum for 10 min. The surviving embryos were transferred into patients on the same day of thawing. RESULTS: Sixty-three embryos were thawed, of which 52 embryos (83%) survived with at least one intact blastomere. Nineteen frozen-thawed embryo transfers were made. The mean embryos per transfer was 2.7. Three pregnancies (16%/transfer) were established. One miscarriage occurred in the eighth week of pregnancy. Two pregnancies went to term and three healthy infants were born. CONCLUSIONS: The present data demonstrate that ultrarapid freezing is a method worth consideration in the area of human embryo freezing.

Abortion, Spontaneous↗

PubMed2005

Comparison of growth rates of fresh and frozen-thawed embryos according to chromosomal status.

PURPOSE: To report a comparison of growth rates between fresh and frozen-thawed embryos on day 3 and 4 according to chromosomal status during PGD. METHODS: Embryos were biopsied on day 3, fluorescent in situ hybridization performed for aneuploidy detection and growth rates monitored. RESULTS: Based on 241 egg pick up-PGD and 133 frozen embryo transfer-PGD cycles. The development rate of embryos despite their chromosomal status was similar on day 3, however, overall, fresh embryos showed a significantly improved development (> or =6 cell stage; 85.7%) compared to frozen embryos (77.0%; p < 0.003). On day 4 fresh embryos showed accelerated development and further developmental improvements were associated with chromosomal normality (56.1% normal vs. 42.2% aneuploid; p < 0.004). CONCLUSIONS: Cryopreservation slows embryo development regardless of the chromosomal status. However, chromosomal status did not influence the chance of embryo implantation which was the same for fresh and thawed embryos.

Cryopreservation↗

PubMed2005

Self-correction of chromosomally abnormal embryos in culture and implications for stem cell production.

OBJECTIVE: To ascertain whether embryos classified by preimplantation genetic diagnosis (PGD) for infertility as abnormal and then plated to obtain stem cells would self-correct partially or totally in culture, producing disomic stem cells. DESIGN: Prospective study to determine the chromosome status of embryos on day 3 and 6, as well as cultured cells derived from inner cell masses from the same embryos when cultured up to day 12. SETTING: Research laboratory. PATIENT(S): Patients undergoing PGD of aneuploidy. INTERVENTION(S): Of 142 embryos classified by PGD for aneuploidy as abnormal, 50 were cultured to the blastocyst stage. At that stage a fraction of the embryos underwent trophectoderm biopsy to reconfirm the PGD diagnosis. After further co-culture with feeders up to day 12, 34 embryos attached to the feeder cells. Of those, 24 were analyzed by fluorescence in situ hybridization (FISH) and the rest for the expression of Oct-4, SSEA-3, SSEA-4, TRA1-60, and TRA1-80. MAIN OUTCOME MEASURE(S): Disomic cells obtained from trisomic embryos. RESULT(S): Analysis by FISH of day-12 cultures showed that 7 were totally normal, 6 were mostly abnormal, and 11 had experienced some chromosome normalization, having between 21% and 88% normal cells. Day-12 culture was positive for Oct-4 expression by reverse transcriptase polymerase chain reaction analysis and for SSEA-3, SSEA-4, TRA1-60, and TRA1-80 by immunocytochemistry. CONCLUSION(S): Chromosome self-normalization occurs in a significant proportion of chromosomally abnormal embryos, possibly because of the loss of a chromosome in trisomic cells after blastocyst stage. Thus chromosomally abnormal embryos are a potential source of disomic stem cells. Not all chromosomally abnormal embryos self-corrected. Abnormal stem cells that might be derived could be used as models to study the effect of chromosomal abnormalities on human development.

Chromosome Aberrations↗

PubMed2006

Embryo quality is more important for younger women whereas age is more important for older women with regard to in vitro fertilization outcome and multiple pregnancy.

OBJECTIVE: To determine the efficiency of embryo scoring systems for multiple pregnancy in women undergoing IVF procedures. DESIGN: Retrospective record analysis. SETTING: University hospital, tertiary medical center. PATIENT(S): Three hundred one patients undergoing controlled ovarian stimulation, IVF/intracytoplasmic sperm injection (ICSI), and day 3 embryo transfer. INTERVENTION(S): IVF/ICSI and embryo transfer. MAIN OUTCOME MEASURE(S): Rate of pregnancy and rate of multiple pregnancy. RESULT(S): The score of the best three embryos (Top3) was more correlated with IVF outcome than were the number of good embryos (P=.009) or the cumulative embryo score (P=.038). In the logistic regression model, Top3 was more relevant to IVF outcome and multiple pregnancy for younger patients than was age (P<.05). For older patients, age was more correlated with IVF outcome and multiple pregnancy than was embryo morphology (P<.05). CONCLUSION(S): The embryo morphology criteria can help reduce the number of embryos transferred into younger patients. We could use the age of patients as an indicator to determine the number of embryos transferred into older patients.

Adult↗

PubMed2006

Predictors of embryo fragmentation and outcome after fragment removal in in vitro fertilization.

OBJECTIVE: To assess predictors of embryo fragmentation in IVF as well as to compare cycle outcomes between low-grade embryos subjected to defragmentation and high-grade embryos not undergoing defragmentation. DESIGN: A retrospective, case-control trial. SETTING: A university hospital IVF program. PATIENT(S): Three hundred twenty-seven nondonor, fresh IVF cycles. MAIN OUTCOME MEASURE(S): Predictors of fragmentation. We evaluated age, basal FSH and E(2) levels, the number of retrieved oocytes, and fertilization rates. Outcome assessments following defragmentation included rates of implantation, clinical pregnancy, spontaneous abortion, and live birth. RESULT(S): Increased age and lower number of oocytes and embryos were associated with embryo fragmentation. Lower-grade embryos after defragmentation yielded rates of implantation, clinical pregnancy, live birth, spontaneous abortion, and fetal defects equivalent to high-grade embryos. CONCLUSION(S): Fragmented embryos correlate with poorer prognosis cycles; however, fragmented embryos that undergo defragmentation result in equivalent clinical outcomes to high-grade, nondefragmented embryos.

Abortion, Spontaneous↗

PubMed2005

Differences in proteinase digestibility of the zona pellucida of in vivo and in vitro derived porcine oocytes and embryos.

Embryo transfer practitioners know very well that, in a variety of species, there are differences between in vitro- and in vivo-derived embryos. It is assumed that these differences are results of suboptimal in vitro conditions leading to cytoplasmic and nuclear imperfections that will result in decreased embryo viability. In the present investigation the resistance of the zona pellucida of in vivo- and ex vivo-derived porcine embryos to a proteolytic enzyme is addressed. Ovulated but unfertilized oocytes, in vitro and in vivo-derived embryos of various developmental stages were exposed to a 0.5% pronase solution. The zonae of ovulated oocytes and in vivo-derived embryos at various stages of development took much longer to be digested than zonae of comparable in vitro-stages. Residence of in vitro derived embryos in an oviduct, no matter whether excised or in situ, significantly increased the zona resistance to pronase digestion. Embryonal stages normally residing in the uterus exhibited a distinctly decreased zona resistance to pronase. The culture of IVF embryos in an excised oviduct brought about a 6- to 14-fold increase in time required for zona digestion. A 24 h residence of IVF-derived embryos in the oviduct of a live recipient resulted in a digestion time for the zona of, on average, 48 h versus 1.4 h in the controls. Individual differences were substantial. The observations suggest that there must be structural changes in the zona pellucida or some sort of protective coating deposited while ova or embryos reside in the oviduct supplying protection against the action of proteolytic enzymes.

Animals↗

PubMed2005

The usefulness of a single measurement of insulin-like growth factor-1 as a predictor of embryo yield and pregnancy rates in a bovine MOET program.

The objective was to determine if a single measurement of plasma insulin-like growth factor-1 (IGF-1) could predict the number of viable embryos obtained from donors and the likelihood of pregnancy in recipients in multiple ovulation and embryo transfer (MOET) programs in cattle. The embryo yields from 101 embryo recoveries were examined in maiden Holstein heifers (n=75) and multiparous Holstein cows (lactating cows n=20, dry cows n=6). Donors were super stimulated with FSH and embryo recovery was done non-surgically 7 days after artificial insemination. Embryos were classified according to the IETS criteria. Pregnancy rates in 100 maiden Holstein heifer recipients were analysed. Recipients were on day 7+/-1 of the estrous cycle at transfer. Pregnancy diagnosis was carried out at day 30 (PD 30) and rechecked at day 60 (PD 60) after transfer. Blood samples from coccygeal vessels taken at the time of embryo recovery (donors) and transfer (recipients) were analysed for IGF-1, insulin, beta-hydroxybutyrate (beta-OHB), non-esterified fatty acids (NEFA), urea and cholesterol. There was a negative correlation between the number of viable embryos and insulin (r=-0.33, P=0.025) in donor heifers. In donor cows, the number of viable embryos was correlated with IGF-1 (r=0.43, P=0.028) and cholesterol (r=-0.43, P=0.027). In recipients, PD30 and PD 60 were not affected by any of the circulating parameters analysed. Insulin, IGF-1 and cholesterol only explained 8.9, 13.9 and 15.8% of the variation in the production of viable embryos, respectively. Several factors affect MOET programs and under the circumstances of the present study the usefulness of hormonal and metabolic profiles as predictors of the outcome of this biotechnology was limited.

3-Hydroxybutyric Acid↗

PubMed1998

Female and male human embryo growth rates are similar before the eight-cell stage.

OBJECTIVE: Our purpose was to assess the possible relationship between human embryo growth rates and sexual differentiation. STUDY DESIGN: We analyzed 142 conceptional in vitro fertilization and embryo transfer cycles undertaken in 137 women (151 embryos transferred) in which each embryo transferred led to a gestational sac. Embryos were sorted into three groups according to the number of blastomeres assessed just before embryo transfers < or = 3, 4, and > or = 5 blastomeres. RESULTS: Percentages of girls and boys remained roughly unaltered irrespective of the number of blastomeres observed just before embryo transfer: < or = 3 blastomeres, 45% and 55%; 4 blastomeres, 44% and 56%; and > or = 5 blastomeres, 45% and 55%, respectively (statistical power 90% at the 5% significance level). CONCLUSIONS: This indicates that embryo growth rates before the eight-cell stage are not related to the sex of the live-born infant, thereby dissuading the use of embryo growth rates in the appraisal of sex likelihood in regular in vitro fertilization-embryo transfer.

Blastomeres↗

PubMed2003

Effect of blastomere loss on the outcome of frozen embryo replacement cycles.

OBJECTIVE: To assess the impact of survival of cryopreservation and thawing with all blastomeres intact on the outcome of frozen embryo replacement (FER) cycles. DESIGN: Prospective observational study. SETTING: University-affiliated tertiary referral assisted conception unit. PATIENT(S): The number of intact blastomeres before cryopreservation and after thawing was prospectively recorded in 1,687 cleavage-stage embryos thawed in 377 FER cycles. The cycles were categorized into two groups: group A (n = 184) included cycles in which all embryos transferred survived the cryopreservation and thawing process with all their original blastomeres intact; group B (n = 193) included cycles in which embryos transferred included at least one partially damaged embryo that has lost up to 50% of its original blastomere number. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Pregnancy and embryo implantation rates. RESULT(S): Groups A and B were comparable with respect to mean age at cryopreservation, mean number of oocytes retrieved and fertilized normally in the fresh cycle, and mean age at frozen transfer. No significant difference was found between the two groups with regard to mean number of frozen and thawed embryos per cycle and mean endometrial thickness reached before P supplementation. More embryos were transferred per cycle in group B than group A (2.4 +/- 0.6 vs. 2.1 +/- 0.6, respectively). However, the pregnancy and clinical pregnancy rates per cycle were significantly higher in group A than in group B (39.1% and 28.3% vs. 22.8% and 13.5%, respectively). The implantation rate was also higher in group A than in group B (17.3% vs. 8.1%, respectively). CONCLUSION(S): FER cycles in which all embryos transferred remained fully intact at thawing achieve a better outcome than those with at least one partially damaged embryo.

Adult↗

PubMed1986

High pregnancy rate after early human embryo freezing.

Human embryos produced by in vitro fertilization (IVF) were frozen with 1,2-propanediol as a cryoprotectant. Embryo survival after thawing was related to the presence of a nucleus in frozen cells and decreased with the increasing number of cells in the frozen embryo. None of five embryos frozen 3 or 4 days after IVF survived when thawed. Of 48 early embryos (35 patients) frozen 1 or 2 days after IVF, 42 (87.5%) were transferred in 32 patients. Ten pregnancies were initiated after frozen embryo transfer (ET). If we exclude the three infertile patients who had sexual intercourse in the fertile period, the pregnancy rate for each patient who had 1- or 2-day frozen embryo(s) was 22% (7 of 32). One of the pregnancies was obtained after ET of a 1-cell pronucleated frozen and thawed embryo. The rate of ongoing pregnancies after triple fresh ET was 23%. In patients having four embryos obtained in a single IVF cycle, the expected overall liveborn rate in an IVF-ET program including embryo cryopreservation could theoretically equal that of natural human fertility.

Cell Survival↗

PubMed1994

Micromanipulation of human embryos to assist hatching.

OBJECTIVE: To determine the effects of zona slitting and subsequent embryo transfer performed on different days of in vitro human embryonic development to allow appropriate application of assisted hatching techniques to clinical IVF-ET. DESIGN: A microsurgical technique was used to make a standardized slit in the zona pellucida of bipronucleate human embryos on day 2, 3, or 5 after oocyte retrieval. A mock ET was performed after the procedure and the rate of blastocyst formation and the process of hatching in each embryo was monitored. SETTING: All embryos used were donated for research by patients attending the IVF Unit at the John Radcliffe Hospital, Oxford, United Kingdom. MAIN OUTCOME MEASURES: The effects of the mock ET on the integrity of zona-slit embryos was documented. The embryos were cultured further and parameters such as blastocyst formation, initiation, and completion of hatching were monitored in all three groups of embryos. RESULTS: The mock ET did not have a detrimental effect on embryos as assessed by their morphology and subsequent blastocyst formation rate. The technique used in this study to make an opening in the zona increased the rate and number of blastocysts hatching in all three groups compared with nonmanipulated controls. However, the day on which the slit was made did not significantly alter the outcome. CONCLUSION: A gap in the zona pellucida of human embryos significantly increases the rate of hatching. Micromanipulative techniques such as zona slitting can be suitably used for this purpose without loss of blastomeres through the gap in the zona or trapping of the embryo during the process of hatching.

Blastocyst↗

PubMed1997

Interleukin-1 beta levels in human embryo culture supernatants and their predictive value for pregnancy.

Interleukin 1 (IL-1) is possibly one factor produced by the embryo that might have a role in the maternal immunological recognition of pregnancy. The purpose of this study was to identify an embryo-related factor suitable for prediction of pregnancy during IVF procedures. For this purpose, IL-1 beta levels were measured in 21 samples of human embryo culture-conditioned media. The average number of embryos per sample was 5 +/- 1. Simultaneously, 16 cell culture media containing 10% autologous serum but no embryos were tested as controls. IL-1 beta levels were measured using the ELISA technique, and the biological activity of IL-1 was measured by means of a C3H/HeJ mice thymocyte proliferation assay. The average IL-1 beta level +/- S.E.M. was 49 +/- 7 pg/ml in embryo culture-conditioned media and 12 +/- 2 pg/ml in controls (P < 0.001). The average IL-1 beta level in embryo culture-conditioned media from viable pregnancy cycles was 82 +/- 6 pg/ml (n = 8), while in those cases that did not result in viable pregnancies the IL-1 beta level was significantly lower (28 +/- 4 pg/ml, n = 13, P < 0.001). The IL-1 activity of embryo culture-conditioned media, measured by [3H]thymidine incorporation in thymocytes was increased, compared with control media (442 +/- 51 counts/min vs. 337 +/- 13 counts/min, P < 0.05), and the highest values corresponded to media containing those embryos that resulted in pregnancies (589 +/- 41 counts/min, P < 0.01 vs. controls). We conclude that the determination of the levels of this cytokine in embryo culture-conditioned media might be a predictive parameter for pregnancies in patients undergoing IVF-ET.

Culture Media, Conditioned↗