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Results for “Fertilization rate”

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PubMed1993

Ovarian stimulation with buserelin/HMG/HCG: prospective randomized study of short versus long protocol.

The combined administration of the gonadotrophin-releasing hormone (GnRH) agonist buserelin and human menopausal gonadotrophin (HMG) was evaluated in 527 cycles (428 patients) of an assisted reproduction programme. All women were randomly allocated according to the ovulation induction protocol into two groups: group I (short protocol; 318 cycles) was given buserelin (1 mg/day) intranasally from cycle day 1 and HMG (2 ampoules/day) from day 3 until human chorionic gonadotrophin (HCG) administration: group II (long protocol; 209 cycles) was given buserelin (1 mg/day) intranasally from cycle day 1 for at least 14 days and then 2 ampoules HMG/day were added, increasing progressively according to the ovarian response. The number (mean +/- SEM) of follicles developed was higher in group II than in group I (9.1 +/- 0.4 versus 7.7 +/- 0.3, respectively; P < 0.05). More oocytes were retrieved in group II (8.4 +/- 0.5) than in group I (6.5 +/- 0.3) (P < 0.001), as well as more embryos (6.3 +/- 0.5 and 4.0 +/- 0.3, respectively; P < 0.001). Moreover, in group II there was a better correlation between oestradiol and the total follicular volume (r = 0.5391) on cycle day 0 compared with group I (r = 0.458), while oestradiol values were similar between the two groups. No differences were observed in the cancellation rate, fertilization rate and maturity of the oocytes between the two groups. The pregnancy rate per transfer was slightly better in group II (25.8%) than in group I (19.4%), but this difference was not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1984

Obstetrics at Galiwin'ku.

A study is presented of the outcome of the 683 deliveries of the Aboriginal women resident on Elcho Island between 1971 and 1982. Comment is made on birth rates, fertility rates, antenatal attendance, risk factors and the outcome of the preterm labours. Current strategies for improving antenatal care are outlined including the use of real time scanning.

Adolescent↗

PubMed1993

Demographic and employment shifts: implications for benefits and economic security.

This Issue Brief examines factors affecting the population's age distribution and composition, such as mortality rates, fertility rates, and immigration. In addition, it examines factors affecting labor force composition, such as immigration, increased labor force participation of women, and retirement trends, and discusses the potential impact of these changes on publicly financed programs: Medicare, Medicaid, Social Security, and federal employee retirement systems. The discussion also highlights the implications of these population and labor force changes on employers, employees, and retirees. The elderly population--now 31.8 million, representing 12.6 percent of the population--is projected to experience tremendous growth between 2010 and 2030, when the baby boom generation reaches age 65, rising from 39.7 million, or 13.3 percent of the population, to 69.8 million, or 20.2 percent of the population. Growth in the elderly population has implications for retirement and health care systems. Population projections suggest that the traditionally pyramid-shaped work force, with a proportionately greater number of younger workers than older workers, will be replaced with a more even age distribution. Consequently, significant and continued modifications to benefit packages, such as changes in compensation structures in which earnings automatically rise with age, are likely to occur. Women's labor force participation began to accelerate in the mid-1950s, rising 75 percent among women aged 25-44 in 1991, although there is some indication that this growth may be flattening. With women comprising a greater part of the labor force, employers will be encouraged to develop and implement programs to better accommodate their needs. Increased life expectancy, a decreased percentage of entry level workers, changes in Social Security's normal retirement age from 65 to 67, and employer plans to raise the normal age of retirement or provide incentives to delay retirement, could raise the average age of retirement. However, other factors, such as poor health, other sources of retirement income, and individual preferences for retirement, could still dominate the retirement decision. The combination of increased average life expectancy guaranteeing more years of retirement to finance and rising dependency ratios increases the future cost of Social Security financing. Medicare financing is also an important policy issue because the program is projected to experience financial difficulties in the short term, resulting from explosive health care costs. In addition, Medicaid expenditures are consuming increasing amount of shrinking state budget resources--a large portion of which is used to finance nursing home care for a growing elderly population.

Age Distribution↗

PubMed1990

[In-vitro rates of fertilization and culture to blastocyst stage of mouse oocytes following co-incubation of murine spermatozoa with Escherichia coli and Ureaplasma urealyticum].

Mouse-spermatozoa were released of the ductus deferens and coincubated with different strains of E. coli resp. U. urealyticum before inseminated with oocytes of superovulated female mice. Daily light microscopic observations of embryonic development took place. Coincubation of spermatozoa with bacteria concentration of 10(3) cfu/ml E. coli revealed no changes in fertilization or culture rates as compared to the uninfected control group. In the same way a coincubation with 10(6) cfu/ml had no influence on the fertilization rates in vitro, however the culture rates were considerably reduced. Only one strain of ureaplasma urealyticum effected after coincubation with spermatozoa a reduced fertilization rate, the embryonic development into blastocysts after in vitro fertilization of spermatozoa infected with ureaplasma urealyticum showed a marked reduction in all but two strains.

Animals↗

PubMed1992

Increased fertilization and pregnancy rate in polypronuclear fertilization cycles in in vitro fertilization-embryo transfer.

OBJECTIVE: To compare fertilization and pregnancy rates between cycles with polypronuclear fertilizations and cycles with normal fertilizations. DESIGN: In vitro fertilization-embryo transfer (IVF-ET) cycles in which oocytes were retrieved were divided into two groups according to the nature of fertilization. PATIENTS: All patients were participants of our IVF-ET program. RESULTS: A significantly higher fertilization rate was found in the polypronuclear fertilization cycles (61% versus 36.6%) and also an improved pregnancy rate (47.5% versus 19.6%) and per embryo transfers (53% versus 28.8%). The vast majority of polypronuclear fertilizations occurred in mature oocytes. CONCLUSION: We believe that the increased receptability of the oocytes improves fertilization and conception rates. The polypronuclear fertilization is an extreme expression of such improved receptibility and should be considered as an encouraging sign for conception.

Embryo Transfer↗

PubMed1993

Abnormal sperm-mucus penetration test predicts low in vitro fertilization ability of apparently normal semen.

OBJECTIVE: To investigate whether Kremer's sperm-mucus penetration test may predict sperm fertilizing ability in IVF. DESIGN: Kremer's test was prospectively performed on semen samples used for 66 consecutive IVF trials and compared with the fertilization rates and fertilization failure rates observed. RESULTS: Fertilization rates were significantly reduced in cases of abnormal Kremer's test (42% versus 51%; n = 745 oocytes with a statistically insignificant increase in fertilization failure rates (21% versus 10%; n = 66 trials). For abnormal semen, fertilization rates (39% versus 39%; n = 208 oocytes) and fertilization failure rates (20% versus 28%; n = 17 trials) were similar regardless of Kremer's test result. For normal semen, an abnormal Kremer's test implied a significant decrease in fertilization rates (44% versus 54%; n = 537 oocytes) with a statistically insignificant increase in fertilization failure rates (21% versus 6%; n = 49 trials). CONCLUSIONS: Abnormal Kremer's test results identify patients with a decreased in vitro fertilizing ability despite apparently normal semen samples and a group with very low fertilizing failure risk in case of normal semen samples and normal Kremer's test. Kremer's test does not add any predictive value to sperm analysis in the case of abnormal semen samples. These observations point out the importance of the male factor in fertilization failure even in the case of normal semen analysis.

Cervix Mucus↗

PubMed1998

[Influences of sperm quality and quantity on fertilization, cleavage rates and quality of embryos in in-vitro fertilization].

OBJECTIVE: To examine the influences of the quality and quantity of seminal sperm and inseminational sperm on in-vitro fertilization (IVF) outcomes. METHODS: chi-square tests were used to analyze the impacts of both semen and inseminated sperm concentrations and percentages of different grade motile sperm on the fertilization rates in 481 matured and 273 immatured oocytes and cleavage rate percentage of embryo with low quality in embryos obtained from 92 IVF-embryo transfer cycles. RESULTS: The fertilization rates of both kinds of oocytes and cleavage rate of fertilizaed matured oocyte significantly decreased (P < 0.05) as the concentrations and percentages of grade a and b sperms in semen reduced. The rates of embryos with abnormal morphology were significantly dropped when the above sperm parameters increased (P < 0.05). Meanwhile, it was also found that the concentration and motility of inseminated sperm could also affect the above three IVF parameters significantly (P < 0.05). CONCLUSION: Highly active semen and inseminated sperm play important roles not only in fertilization, but also in cleavage and embryo development during IVF procedure.

Cleavage Stage, Ovum↗

PubMedDate not supplied

[Epidemiological study of fertility in adolescents in the Autonomous Community of Madrid].

OBJECTIVE: The purpose of this study was to research the frequency and distribution of fertility in adolescence and, in looking at different environments within the Autonomous Community of Madrid (ACM), to evaluate the relationship of fertility rates to determined variables of a socio-economic, educational and demographic nature. DESIGN: An observational crossover study was carried out. SETTING: Autonomous Community of Madrid. PATIENTS AND OTHERS PARTICIPANTS: In this study, the specific rate of fertility in adolescents (SRFA) was calculated and the correlation between the SRFA and variables of a socioeconomic, educational and demographic nature were analysed by means of the multiple linear regression method. MEASUREMENTS AND MAIN RESULTS: We found important differences in the distribution of fertility within the ACM. There was also a positive correlation (p < 0.05) between the SRFA and those variables which expressed the percentages of illiteracy, industrial workers and with the synthetic youth index. A negative correlation (p < 0.05) was found for the percentages of graduates, professionals and technicians, managers and directors and with the synthetic ageing index. We found no correlation with the unemployment index. On applying the multivariant model, the variable that weighed most on fertility was the level of education, which was in our case measured by the percentage of illiteracy. CONCLUSIONS: We found an uneven spread of adolescents' fertility rates in the Autonomous Community of Madrid. The fertility rates were higher in those boroughs where there was more illiteracy.

Adolescent↗

PubMed2005

Effects of the ovulatory serum concentration of human chorionic gonadotropin on the incidence of ovarian hyperstimulation syndrome and success rates for in vitro fertilization.

OBJECTIVE: To determine whether the serum concentration of hCG on the day after hCG administration (abbreviated throughout this article as [hCG]) is related to the incidence of ovarian hyperstimulation syndrome (OHSS), oocyte recovery per follicle, fertilization, blastulation, embryo transfer, implantation, and clinical pregnancy. DESIGN: Retrospective study. SETTING: Private infertility clinic. PATIENT(S): The OHSS study group included 849 non-donor IVF cycles performed between January 1998 and August 2003. The study group for hCG efficacy included 248 nondonor IVF cycles performed between January 2001 and May 2003 with patients younger than 35 years of age. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Occurrence of OHSS, severity of OHSS, [hCG], proportion of follicles yielding oocytes, fertilization rate, blastulation rate, transfer rate, implantation rate, and clinical pregnancy rate. RESULT(S): No significant relationships were observed between [hCG] and the proportion of follicles yielding oocytes, fertilization rate, blastulation rate, or the probabilities of embryo transfer, implantation, or clinical pregnancy. The incidence of OHSS (all types) and OHSS requiring transvaginal paracentesis were predicted by [hCG] (P=.02 and P=.05, respectively) and with follicle count (P<.0001 in both cases). CONCLUSION(S): These results suggest that moderated hCG dosage is useful in preventing OHSS without reducing efficacy.

Adult↗

PubMed2004

[Treatment option for unexplained primary infertility following failed intrauterine insemination].

OBJECTIVE: To determine an optimal insemination technique for unexplained infertility patients undergoing IVF or ICSI following failed intrauterine insemination (IUI). METHODS: Sixty-five cycles of 61 patients with failed IUI were divided into four groups: Group A (37 cycles of IVF), Group B (19 cycles of ICSI), Group C (4 cycles of IVF and ICSI: half and half), Group D (5 cycles of ICSI after failed IVF). The conventional IVF cycles were defined as Group E (37 cycles), and the conventional ICSI cycles defined as Group F (24 cycles). The fertilization rate, completely failed fertilization rate, high quality embryo rate, clinical pregnancy rate and the implantation rate were compared among all the groups. RESULTS: There were statistically significant differences in the fertilization rate, completely failed fertilization rate between Groups A and E (55.4% vs 72.8%, P < 0.05; 21.6% vs 0%, P < 0.005), and Groups A and B (55.4% vs 68.4%, P < 0.05; 21.6% vs 0%, P < 0.01). In Group D, there was statistically significant difference in the fertilization rate between IVF cycles and ICSI cycles (12.2% vs 74.2%, P < 0.005). CONCLUSION: The present study demonstrates that there may be 20% of totally failed fertilization in IVF cycles with unexplained primary infertility following failed IUI, and ICSI treatment can increase fertilization rate and avoid complete fertilization failure.

Adult↗

PubMed1995

Failed fertilization in vitro: second day micromanipulation of oocytes versus reinsemination.

OBJECTIVE: To compare routine reinsemination with 2nd day micromanipulation in patients with poor day 1 fertilization. DESIGN: A retrospective review of patient records. SETTING: The Mount Sinai Medical Center Assisted Reproductive Technologies Program. PARTICIPANTS: Patients undergoing IVF-ET who had poor fertilization (< 35%) with standard insemination and underwent second day reinsemination of oocytes (group I, n = 84) compared with patients who underwent 2nd day micromanipulation with subzonal insemination (group II, n = 12). MAIN OUTCOME MEASURES: Fertilization rate, cleavage rate, number of embryo transfers, and pregnancy rate. RESULTS: Fertilization rate and cleavage rate were significantly higher in group II patients. Pregnancies per transfer were similar between groups I (3/21, 14.3%) and II (0/9, 0%). Second day fertilization was possible in 9 of 12 group II patients, and fertilization rate was higher than day 1 in all nine, however, only 50% achieved cleavage, and none achieved pregnancy. CONCLUSIONS: Although micromanipulating oocytes that fail to fertilize may identify occult male factor infertility, may help the clinician plan future cycles, and may result in fertilization and even transfer of embryos in some cycles, there were no pregnancies in our series, and, for now, the clinical efficacy of this procedure remains in question.

Cleavage Stage, Ovum↗

PubMed1986

The influence of dietary copper on reproduction, growth and the cardiovascular system in Swiss-Webster female mice.

One hundred forty pubertal Swiss-Webster female mice (Mus musculus) were assigned randomly to a purified diet modified to contain 1, 2, 3, 4, 5 and 6 ppm copper as copper carbonate (Diets 1 thru 6, respectively). Diet 7 was a commercial rodent laboratory diet containing 11 ppm copper. Following 60 days of prefeeding, the breeding regimen was initiated by introducing a proven breeder male into each cage of 10 females in the afternoon and removing them the next morning. The breeding regimen was conducted for 28 days and females were either sacrificed at 24 or 96 hours following detection of a vaginal plug. Body weight, hematocrit, heart weight, hemoglobin concentration, ova recovery rate and fertilization rate were recorded for each female. All morphologically normal embryos collected 24 hours after detection of the vaginal plug were cultured and development in vitro evaluated. Body weight, hemoglobin concentration and hematocrit were lower (P less than .05), and heart weight and percent body weight occupied by the heart (%BWOH) were higher (P less than .05) in mice fed Diet 1. Heart weight and %BWOH were not different among mice fed Diets 2 thru 6 (P greater than .05). Ova recovery rate and fertilization rate were significantly reduced in mice maintained on Diet 1. The incidence of in vitro blastocyst formation was lower in embryos collected from females fed Diets 1 and 3 (P less than .05). Blastocyst hatching in vitro was not observed in embryos from females maintained on Diet 1, and was greater in embryos from females fed Diets 4, 5, and 7 (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

A comparative prospective study using matched samples to determine the influence of subnormal hypo-osmotic test scores of spermatozoa on subsequent fertilization and pregnancy rates following in-vitro fertilization.

The achievement of pregnancies in vivo is rare in couples where the male partner has defective sperm membranes as shown by hypo-osmotic swelling (HOS) test scores of < 50%. However, there have been mixed reports on the value of the HOS test in predicting outcome following invitro fertilization; some studies suggest reduced fertilization rates and others find little, if any, predictability of decreased fertilization. The assumption has been made that fertilization rates are proportional to pregnancy rates; however, this may not necessarily be true since defective spermatozoa could lead to a less viable pre-embryo and therefore a decreased viable pregnancy rate. We performed a comparative prospective study using matched controls to evaluate fertilization rates and to determine subsequent pregnancy rates. The mean HOS scores were 70.0 and 36.7% respectively, with mean motile sperm concentrations of 35.7 and 34.0 x 10(6)/ml in 27 matched pairs. There was no difference in the mean number of oocytes retrieved, fertilization rates or number of embryos transferred between the two groups by HOS score. The clinical and viable pregnancy rates and implantation rates were 25.9, 18.5 and 9.9% for normal versus 3.7, 3.7 and 1.1% for subnormal groups. These data suggest that low HOS scores may be associated with the formation of defective embryos, leading to low pregnancy rates but normal fertilization rates.

Female↗

PubMed1989

Effects of follicle-stimulating hormone and ovarian steroids during in vitro meiotic maturation on fertilization of rat oocytes.

The present study examined the effects of gonadotropins and ovarian steroids during in vitro meiotic maturation of rat oocytes on their ability to undergo in vitro fertilization. Fully grown oocytes were isolated from antral follicles of immature rats and cultured as oocyte-cumulus cell complexes (OCC) under conditions in which completion of meiotic maturation occurs spontaneously. They were then exposed to spermatozoa under conditions in which oocytes matured in vivo exhibit high fertilization rates. Compared with oocytes from pregnant mare's serum gonadotropin (PMSG) or follicle-stimulating hormone (FSH)-treated rats, a similar proportion of the oocytes (greater than 80%) from untreated rats underwent germinal vesicle breakdown, but such oocytes had a lower rate of fertilization (70% vs. 20%). The presence of FSH during in vitro maturation restored the fertilization rate for oocytes from untreated rats, while a cytochrome P450 inhibitor, aminoglutethimide phosphate abolished this beneficial effect of FSH. The addition of progesterone during the in vitro maturation period duplicated the beneficial effect of FSH on fertilization rate of oocytes from untreated rats; oestradiol-17 beta was less effective in this regard, and 5 alpha-dihydrotestosterone was ineffective. These findings indicate that FSH and progesterone, although having no apparent effect on nuclear maturation of the oocyte, play an important role during oocyte maturation in enabling normal fertilization to occur.

Animals↗

PubMed1994

Fertilization efficiency of morphologically abnormal spermatozoa in assisted reproduction is further impaired by antisperm antibodies on the male partner's sperm.

OBJECTIVE: To investigate the influence of antisperm antibodies on the sperm surface on the outcome of IVF and GIFT. DESIGN: Matched controlled retrospective review of two large series. SETTING: Reproductive endocrine divisions of two level-three academic centers. PATIENTS: Twenty-nine male factor patients (38 IVF cycles) showing positive antisperm antibodies on the sperm by immunobead test treated by IVF at the Norfolk program and 56 similar patients (57 cycles) treated by GIFT at the Tygerberg program. Twenty-nine male factor patients (29 IVF cycles) with negative antisperm antibodies screening matched by wife's stimulation protocol and baseline semen analysis characteristics were used as controls in Norfolk; 56 GIFT patients (56 GIFT cycles) matched similarly were the Tygerberg controls. Study and control groups were divided according to sperm morphology pattern in normal, good, and poor prognosis subgroups for comparison. MAIN OUTCOME MEASURES: Fertilization rate of preovulatory oocytes used in IVF in Norfolk and of GIFT supernumerary preovulatory oocytes in Tygerberg; total and term pregnancy rates (PRs) and abortion rates. RESULTS: Fertilization rate was significantly lower in the IVF (41.9% +/- 2.8%) as well as in the GIFT (26.8% +/- 3.8%) (mean +/- SE) study groups than in the respective control groups (73.1% +/- 3.9% and 61.8% +/- 3.9%). Total and term PRs in IVF per cycle (21.1% +/- 6.6%; 13.2% +/- 5.5%) and per transfer (23.5% +/- 7.4%; 14.7% +/- 6.1%), and in GIFT (25.0% +/- 5.8%; 19.6% +/- 5.3%) in the study groups were also lower when compared with their control counterparts (IVF per cycle: 62.1% +/- 6.2% and 41.4% +/- 6.0%; IVF per transfer: 41.9% +/- 2.0% and 27.9% +/- 1.9%; GIFT: 31.6% +/- 6.2% and 28.1% +/- 6.0%), but the difference did not reach statistical significance. Abortion rates were similar in the IVF study group (37.5% +/- 17.1%) and its control groups (39.9% +/- 11.5%). The abortion rate in the GIFT study group was 14.3% +/- 9.4%, and no abortions were recorded in the control group (not significant). CONCLUSIONS: The presence of antisperm antibodies on the sperm surface per se impairs the outcome of assisted reproduction, mainly in terms of fertilization rate of preovulatory oocytes, and possibly in terms of total and term PRs. This holds true regardless of the impact of other semen parameters, particularly the morphology of the sperm within the semen sample.

Abortion, Spontaneous↗

PubMed1999

Prediction of the rates of fertilization, cleavage, and pregnancy success by cumulus-coronal morphology in an in vitro fertilization program.

OBJECTIVE: To examine the relation between the grading of cumulus-coronal morphology at oocyte retrieval and the rates of fertilization, cleavage, and pregnancy success in IVF-ET cycles. DESIGN: Retrospective study. SETTING: University-affiliated medical center. PATIENT(S): Infertile women who underwent IVF-ET treatment. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Fertilization and cleavage of the oocytes and the pregnancy outcome. RESULT(S): Mature grade 3 cumulus-oocyte complexes (COCs) constituted the highest percentage among all grades and had a higher fertilization rate than COCs of other grades (77% versus 65%, 43%, and 28% for grades 2, 1, and 4, respectively). The cleavage and polyspermy rates did not correlate with cumulus-coronal morphology grading. The pregnancy rate was higher in cycles with >50% grade 3 COCs than in cycles with < or =50% grade 3 COCs (32% versus 16%). In cycles with >80% grade 3 COCs, the pregnancy rate was 57%. The correlation between the percentage of grade 3 COCs and the pregnancy rate was independent of patient age and the number of COCs retrieved. CONCLUSION(S): The cumulus-coronal morphology grade correlates with the fertilization rate but not with the cleavage or polyspermy rate. In vitro fertilization cycles that have a greater percentage of grade 3 COCs have an increased chance of resulting in pregnancy. The cumulus-coronal morphology grade predicts pregnancy success in IVF-ET cycles.

Adult↗

PubMed2000

Improved indicators of infant mortality for integrated primary healthcare programmes.

Mortality and fertility rates are decreasing rapidly in many developing countries. It is argued that the indices commonly used as measures of these changes, i.e. infant mortality rate and fertility rate, ignore the interaction between mortality and fertility, and do not reflect their combined impact in lowering overall infant mortality. The paper proposes new indicators of infant mortality, termed fertility-adjusted infant mortality ratio (FIMR), age-specific, fertility-adjusted IMR (AFIMR), and total infant mortality ratio (TIMR) that are more sensitive to rapid demographic changes. These indicators include the combined effects of changes in both fertility and infant mortality rates on overall infant mortality in a region and appear to measure the effects of integrated health programmes better. Further, these conceptualize the mother-infant pair as an appropriate unit with which to monitor mortality, and may be used for guiding allocation of resources intended to lower infant mortality. The application and usefulness of these indicators have been illustrated, using one hypothetical example and empirical data from the maternal-child health and family-planning programme in Matlab, Bangladesh, as well as data from white and black population groups in the U.S.A. The results of these examples demonstrate that the new indicators are more sensitive than traditional measures when describing infant mortality, and may better reflect the perception in infant mortality status in the community.

Adolescent↗

PubMed1994

Quick freezing of unfertilized mouse oocytes using ethylene glycol with sucrose or trehalose.

Unfertilized mouse oocytes were frozen by directly plunging them into liquid nitrogen vapour after equilibration in a freezing medium containing 3 mol ethylene glycol l-1 with 0.25 mol sucrose or trehalose l-1 for 5-40 min. After thawing and dilution of the cryoprotectant, oocytes of normal morphology were inseminated in vitro and the effect of equilibration period on the rates of fertilization and development in vitro was examined. Regardless of the equilibration in the freezing medium, no significant difference was observed on the fertilization rate of frozen-thawed oocytes. However, higher fertilization and higher normal fertilization rates were obtained with equilibration in 3 mol ethylene glycol l-1 with either 0.25 mol sucrose l-1 or trehalose for 20 and 40 min than with 5 and 10 min equilibration. Development rates to two-cell embryos and expanded blastocysts of in vitro fertilized frozen-thawed oocytes that were equilibrated in the freezing medium for 20 and 40 min were significantly higher (P < 0.05 or P < 0.01) than with 5 min equilibration. Development in vivo was assessed by transferring blastocysts derived from unfertilized oocytes frozen by the optimum treatment (20 min equilibration in the freezing medium before freezing) into the uterine horns of day 3 pseudopregnant female recipients. The development rate of frozen-thawed oocytes to the blastocyst stage after insemination in vitro was significantly lower than that of the non-frozen control (P < 0.001). However, transfer of the blastocysts derived from frozen-thawed oocytes to the uterine horns of the recipients in fetal development and implantation rates similar to those of the control.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗